共查询到20条相似文献,搜索用时 15 毫秒
1.
Marylène Bertrand André Brack 《International journal of peptide research and therapeutics》1997,4(4-6):387-389
Summary Alternating poly(Glu-Leu) exhibits a random coil structure in pure water at neutral pH. The addition of 0.5 equiv of Ca2+ induces a coil-to-β-sheet transition and the addition of 0.15 equiv of Fe3+ induces a coil-to-α-helix transition. Conformational competition between these two structures was studied by mixing preformed
β-sheets and α-helices in different proportions. Circular dichroism spectra clearly show that β-sheets are favored at the
expense of α-helices in β-sheet-rich mixtures. 相似文献
2.
Complexes formed by reduced glutathione (GSH) with metal cations (Cr2+, Mn2+,Fe2+,Co2+,Ni2+,Cu2+,Zn2+,Cd2+,Hg2+) were systematically investigated by the density functional theory (DFT). The results showed that the interactions of the metal cations with GSH resulted in nine different stable complexes and many factors had an effect on the binding energy. Generally, for the same period of metal ions, the binding energies ranked in the order of Cu2+>Ni2+>Co2+>Fe2+>Cr2+>Zn2+>Mn2+; and for the same group of metal ions, the general trend of binding energies was Zn2+>Hg2+>Cd2+. Moreover, the amounts of charge transferred from S or N to transition metal cations are greater than that of O atoms. For Fe2+,Co2+,Ni2+,Cu2+,Zn2+,Cd2+ and Hg2+ complexes, the values of the Wiberg bond indices (WBIs) of M-S (M denotes metal cations) were larger than that of M-N and M-O; for Cr2+ complexes, most of the WBIs of M-O in complexes were higher than that of M-S and M-N. Furthermore, the changes in the electron configuration of the metal cations before and after chelate reaction revealed that Cu2+, Ni2+,Co2+ and Hg2+ had obvious tendencies to be reduced to Cu+,Ni+,Co+ and Hg+ during the coordination process. 相似文献
3.
Jarvet J Danielsson J Damberg P Oleszczuk M Gräslund A 《Journal of biomolecular NMR》2007,39(1):63-72
NMR spectroscopy combined with paramagnetic relaxation agents was used to study the positioning of the 40-residue Alzheimer
Amyloid β-peptide Aβ(1–40) in SDS micelles. 5-Doxyl stearic acid incorporated into the micelle or Mn2+ ions in the aqueous solvent were used to determine the position of the peptide relative to the micelle geometry. In SDS solvent,
the two α-helices induced in Aβ(1–40), comprising residues 15–24, and 29–35, respectively, are surrounded by flexible unstructured
regions. NMR signals from these unstructured regions are strongly attenuated in the presence of Mn2+ showing that these regions are positioned mostly outside the micelle. The central helix (residues 15–24) is significantly
affected by 5-doxyl stearic acid however somewhat less for residues 16, 20, 22 and 23. This α-helix therefore resides in the
SDS headgroup region with the face with residues 16, 20, 22 and 23 directed away from the hydrophobic interior of the micelle.
The C-terminal helix is protected both from 5-doxyl stearic acid and Mn2+, and should be buried in the hydrophobic interior of the micelle. The SDS micelles were characterized by diffusion and 15N-relaxation measurements. Comparison of experimentally determined translational diffusion coefficients for SDS and Aβ(1–40)
show that the size of SDS micelle is not significantly changed by interaction with Aβ(1–40).
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
4.
Chin-An Hsu Roch-Chui Yu Cheng-Chun Chou 《World journal of microbiology & biotechnology》2006,22(4):355-361
Summary β-galactosidase from Bifidobacterium longum CCRC 15708 was first extracted by ultrasonication then purified by Q Fast-Flow chromatography and gel chromatography on a
Superose 6 HR column. These steps resulted in a purification of 15.7-fold, a yield of 29.3%, and a specific activity of 168.6 U mg−1 protein. The molecular weight was 357 kDa as determined from Native-PAGE. Using o-nitrophenyl-β-d-galactopyranoside (ONPG) as a substrate, the pH and temperature optima of the purified β-galactosidase were 7.0 and 50 °C,
respectively. The enzyme was stable at a temperature up to 40 °C and at pH values of 6.5–7.0. K
m and V
max for this purified enzyme were noted to be 0.85 mM and 70.67 U/mg, respectively. Na+ and K+ stimulated the enzyme up to 10-fold, while Fe3+, Fe2+, Co2+, Cu2+, Ca2+, Zn2+, Mn2+ and Mg2+ inhibited the activity of β-galactosidase. Furthermore, although glucose, galactose, maltose, or raffinose exerted little
or no effect on the β-galactosidase activity, lactose and fructose inhibited the enzyme activity. The effect of lactose on
the enzyme activity for ONPG is probably a case of competitive inhibition.
A relatively high specific activity of β-galactosidase from B. longum CCRC 15708 could be obtained by Q Fast-Flow chromatography and gel chromatography on a Superose 6 HR column. In some aspects,
particularly the activation by monovalent cations, the properties of β-galactosidase of B. longum CCRC 15708 are different from those obtained from other sources.
Data collected in the present study are of value and indispensable when β-galactosidase from B. longum CCRC 15708 is employed in practical application. 相似文献
5.
Methods of quantum chemistry have been applied to double-charged complexes involving the transition metals Ni2+, Cu2+ and Zn2+ with the aromatic amino acids (AAA) phenylalanine, tyrosine and tryptophan. The effect of hydration on the relative stability
and geometry of the individual species studied has been evaluated within the supermolecule approach. The interaction enthalpies,
entropies and Gibbs energies of nine complexes Phe•M, Tyr•M, Trp•M, (M = Ni2+, Cu2+ and Zn2+) were determined at the Becke3LYP density functional level of theory. Of the transition metals studied the bivalent copper
cation forms the strongest complexes with AAAs. For Ni2+and Cu2+ the most stable species are the NO coordinated cations in the AAA metal complexes, Zn2+cation prefers a binding to the aromatic part of the AAA (complex II). Some complexes energetically unfavored in the gas-phase are stabilized upon microsolvation. 相似文献
6.
Ana Flávia Azevedo Carvalho Maurício Boscolo Roberto da Silva Henrique Ferreira Eleni Gomes 《Journal of microbiology (Seoul, Korea)》2010,48(4):452-459
An α-glucosidase enzyme produced by the fungus Thermoascus aurantiacus CBMAI 756 was purified by ultra filtration, ammonium sulphate precipitation, and chromatography using Q Sepharose, Sephacryl
S-200, and Superose 12 columns. The apparent molecular mass of the enzyme was 83 kDa as determined in gel electrophoresis.
Maximum activity was observed at pH 4.5 at 70°C. Enzyme showed stability stable in the pH range of 3.0–9.0 and lost 40% of
its initial activity at the temperatures of 40, 50, and 60°C. In the presence of ions Na+, Ba2+, Co2+, Ni2+, Mg2+, Mn2+, Al3+, Zn2+, Ca2+ this enzyme maintained 90–105% of its maximum activity and was inhibited by Cr3+, Ag+, and Hg2+. The enzyme showed a transglycosylation property, by the release of oligosaccharides after 3 h of incubation with maltose,
and specificity for short maltooligosaccharides and α-PNPG. The Km measured for the α-glucosidase was 0.07 μM, with a Vmax of 318.0 μmol/min/mg. 相似文献
7.
Subunit E of the vacuolar ATPase (V-ATPase) contains an N-terminal extended α helix (Rishikesan et al. J Bioenerg Biomembr
43:187–193, 2011) and a globular C-terminal part that is predicted to consist of a mixture of α-helices and β-sheets (Grüber et al. Biochem
Biophys Res Comm 298:383–391, 2002). Here we describe the production, purification and 2D structure of the C-terminal segment E133-222 of subunit E from Saccharamyces cerevisiae V-ATPase in solution based on the secondary structure calculation from NMR spectroscopy studies. E133-222 consists of four β-strands, formed by the amino acids from K136-V139, E170-V173, G186-V189, D195-E198 and two α-helices,
composed of the residues from R144-A164 and T202-I218. The sheets and helices are arranged as β1:α1:β2:β3:β4:α2, which are
connected by flexible loop regions. These new structural details of subunit E are discussed in the light of the structural
arrangements of this subunit inside the V1- and V1VO ATPase. 相似文献
8.
Investigation of the influence of divalent metal cations on the induction of plasminogen catalytic activity by monoclonal
antibody IV-Ic showed that the presence of metal cations in the reaction medium changes the induction by slowing down or accelerating
the process. Ions of Zn2+, Mn2+, and Cu2+ completely inhibit activation. Ions of Co2+ and Ni2+ decrease the rate of the first and second phases of the reaction more than 2 times. Ca2+ ions do not have any effect on the activation rate. Ions of Mg2+, Ba2+, and Sr2+ increase the rate of the first phase of the reaction by 1.5, 2.0, and 2.0 times and the rate of the second phase by 2.0,
3.8, and 4.7 times, correspondingly. Sr2+ ions have the strongest stimulating effect on plasminogen activation by monoclonal antibody IV-Ic. Investigation of the dose
dependent effect of Sr2+ on the rate of plasminogen activation by monoclonal antibody IV-Ic showed stimulating effect of Sr2+ at concentrations from 0.1 to 1.0 mM with half maximum at 0.6 mM. However, Sr2+ ions do not affect amidolytic activity of plasmin and activation of plasminogen by streptokinase. Sr2+ ions also do not affect monoclonal antibody IV-Ic binding to plasminogen. The effect of Sr2+ is specific and mediated by the IV-Ic component. The presence of metal cations affects conformational changes in the process
of active site formation. Metal cations also affect structure of the plasminogen molecule active site in the complex with
monoclonal antibody IV-Ic and enzyme-substrate interaction. The effect of α2-antiplasmin on the induction of plasminogen catalytic activity by monoclonal antibody IV-Ic in range of concentrations from
5 to 30 nM has been studied. α2-Antiplasmin at concentration 30 nM almost completely inhibits induction of plasminogen catalytic activity by monoclonal antibody
IV-Ic at the ratio plasminogen/α2-antiplasmin of 3:1. This can be explained by competition of α2-antiplasmin and monoclonal antibody IV-Ic for the lysine-binding sites of plasminogen and inhibition of the active center
in activated complex plasminogen*—mAB IV-Ic. Divalent metal cations and α2-antiplasmin are important factors in induction of plasminogen catalytic activity by monoclonal antibody IV-Ic.
Published in Russian in Biokhimiya, 2006, Vol. 71, No. 6, pp. 778–785. 相似文献
9.
Cordially dedicated to Dr. Leslie Orgel on the occasion of his 70th birthday.Sequential oligo- and polypeptides based on glutamic acid and leucine residues have been synthesized. In pure water, they exhibit a random coil conformation. Addition of very small amounts of divalent metallic cations induces the formation of ordered structure in the peptides which remain in solution. Higher salt concentrations precipitate the peptides. Polypeptides with alternating glutamic acid and leucine residues undergo a coil to -sheet transition in the presence of Ca2+, Ba2+, Mn2+, Co2+, Zn2+ and Hg2+. Addition of Cu2+ or Fe2+ induces the formation of an -helix. Solid amorphous CdS generates water soluble -sheets, as well. Sequential poly(Leu-Glu-Glu-Leu) adopts an -helix in the presence of divalent cations. The sequence-dependent conformational diversity was extended to poly(Asp-Leu) and poly(Leu-Asp-Asp-Leu). 相似文献
10.
Salam A. Ibrahim Awfa Y. Alazzeh Saddam S. Awaisheh Danfeng Song Abolghasem Shahbazi Amer A. AbuGhazaleh 《Biological trace element research》2010,136(1):106-116
The hydrolysis of oligosaccharides and lactose is of great importance to the food industry. Normally, oligosaccharides like
raffinose, stachyose, and verbascose which are rich in different plants like soy bean are considered indigestible by the human
gut. Moreover, many humans suffer from lactose intolerance due to the absence of effective enzyme that can digest lactose.
α-Galactosidase can digest oligosaccharides like raffinose, while β-galactosidases can hydrolyze lactose. Therefore, selection
of microorganisms safe for human use and capable of producing high levels of enzymes becomes an attractive task. The objective
of this study was to investigate the enhancement of α- and β-galactosidase activity in Lactobacillus reuteri by different metal ions. Ten millimolar of Na+, K+, Fe2+, and Mg2+ and 1 mM of Mn2+ were added separately to the growth culture of six strains of L. reuteri (CF2-7F, DSM20016, MF14-C, MM2-3, MM7, and SD2112). Results showed that L. reuteri CF2-7F had the highest α- and β-galactosidase activity when grown in the medium with added Mn2+ ions (22.7 and 19.3 Gal U/ml, respectively). 0.0274% of Mn2+ ions lead to 27, 18% enhancement of α- and β-galactosidase activity over the control group, and therefore, it could be added
to the growth culture of CF2-7F to produce enhanced levels of α- and β-galactosidase activity. The addition of Fe2+ led to a significant (P < 0.01) decrease in the activity of both enzymes for most strains. This study shows that modified culture medium with that
0.0274% Mn2+ can be used to promote the production for α- and β-galactosidase in L. reuteri CF2-7F, which may lead to enhancement of α- and β-galactosidase activity and have a good potential to be used in the food
industry. 相似文献
11.
A. Rehman Farah R. Shakoori A. R. Shakoori 《World journal of microbiology & biotechnology》2008,24(1):47-53
The heavy metal resistant ciliate, Stylonychia mytilus, isolated from industrial wastewater has been shown to be potential bioremediator of contaminated wastewater. The ciliate
showed tolerance against Zn2+ (30 μg/mL), Hg2+ (16 μg/mL) and Ni2+ (16 μg/mL). The metal ions slowed down the growth of the ciliate as compared with the culture grown without metal stress.
The reduction in cell population was 46% for Cd2+, 38% for Hg2+, 23% for Zn2+, 39% for Cu2+ and 51% for Ni2+ after 8 days of metal stress. S. mytilus reduced 91% of Cd2+, 90% of Hg2+ and 98% of Zn2+ from the medium after 96 h of incubation in a culture medium containing 10 μg/mL of the respective metal ions. Besides this,
the ciliate could also remove 88% of Cu2+ and 73% Ni2+ from the medium containing 5 μg/mL of each metal after 96 h. The ability of Stylonychia to take up variety of heavy metals from the medium could be exploited for metal detoxification and environmental clean-up
operations. 相似文献
12.
SlyD belongs to the FK506-binding protein (FKBP) family with both peptidylprolyl isomerase (PPIase) and chaperone activities,
and is considered to be a ubiquitous cytosolic protein-folding facilitator in bacteria. It possesses a histidine- and cysteine-rich
C-terminus binding to selected divalent metal ions (e.g., Ni2+, Zn2+), which is important for its involvement in the maturation processes of metalloenzymes. We have determined the solution structure
of C-terminus-truncated SlyD from Helicobacter pylori (HpSlyDΔC). HpSlyDΔC folds into two well-separated, orientation-independent domains: the PPIase-active FKBP domain and the chaperone-active
insert-in-flap (IF) domain. The FKBP domain consists of a four-stranded antiparallel β-sheet with an α-helix on one side,
whereas the IF domain folds into a four-stranded antiparallel β-sheet accompanied by a short α-helix. Intact H. pylori SlyD binds both Ni2+ and Zn2+, with dissociation constants of 2.74 and 3.79 μM respectively. Intriguingly, binding of Ni2+ instead of Zn2+ induces protein conformational changes around the active sites of the FKBP domain, implicating a regulatory role of nickel.
The twin-arginine translocation (Tat) signal peptide from the small subunit of [NiFe] hydrogenase (HydA) binds the protein
at the IF domain. Nickel binding and the recognition of the Tat signal peptide by the protein suggest that SlyD participates
in [NiFe] hydrogenase maturation processes. 相似文献
13.
The α1 subunit coding for the human brain type E calcium channel (Schneider et al., 1994) was expressed in Xenopus oocytes in the absence, and in combination with auxiliary α2δ and β subunits. α1E channels directed with the expression of Ba2+ whole-cell currents that completely inactivated after a 2-sec membrane pulse. Coexpression of α1E with α2bδ shifted the peak current by +10 mV but had no significant effect on whole-cell current inactivation. Coexpression of α1E with β2a shifted the peak current relationship by −10 mV, and strongly reduced Ba2+ current inactivation. This slower rate of inactivation explains that a sizable fraction (40 ± 10%, n= 8) of the Ba2+ current failed to inactivate completely after a 5-sec prepulse. Coinjection with both the cardiac/brain β2a and the neuronal α2bδ subunits increased by ≈10-fold whole-cell Ba2+ currents although coinjection with either β2a or α2bδ alone failed to significantly increase α1E peak currents. Coexpression with β2a and α2bδ yielded Ba2+ currents with inactivation kinetics similar to the β2a induced currents, indicating that the neuronal α2bδ subunit has little effect on α1E inactivation kinetics. The subunit specificity of the changes in current properties were analyzed for all four β subunit
genes. The slower inactivation was unique to α1E/β2a currents. Coexpression with β1a, β1b, β3, and β4, yielded faster-inactivating Ba2+ currents than currents recorded from the α1E subunit alone. Furthermore, α1E/α2bδ/β1a; α1E/α2bδ/β1b; α1E/α2bδ/β3; α1E/α2bδ/β4 channels elicited whole-cell currents with steady-state inactivation curves shifted in the hyperpolarized direction. The
β subunit-induced changes in the properties of α1E channel were comparable to modulation effects reported for α1C and α1A channels with β3≈β1b > β1a≈β4≫β2a inducing fastest to slowest rate of whole-cell inactivation.
Received: 27 March 1997/Revised: 10 July 1997 相似文献
14.
The effect of salts (nitrates, chlorides, and sulfates) of microelements, Cd2+, Ni2+, and Co2+ and the effect of boric acid and ammonium molybdate on phosphate uptake by maize root cortex segments were tested.
Higher concentration (0.1 mM) of Cu2+ salts caused enhancement of phosphate efflux to the extent that efflux was higher than influx.
Inhibitory action on phosphate uptake by maize root cortex segments was exerted by following salts: 0.01 mM Cu2+ salts (20–30% inhibition), 0.5 mM ZnSO4 (9.7%), 0.5 and 0.05 mM ZnCl2 (34.3% and 20.8%), 0.1 mM salts of Cd2+, Ni2+, Co2+ (35–78%).
1 mM FeSO4 had significant stimulatory effect (92%) on phosphate uptake. Much weaker stimulatory effect was exerted by 1 mM FeCl3 (14%), 0.05 mM ZnSO4 (9.6%), 0.005 mM ZnCla and ZnSO4 (8.4 and 18.5%) and 0.001 mM CdCl2 and CdSO4 (20.8 and 12.4%).
All other tested salts-salts of Mn2+ (0.1 and 0.01 mM), 0.01 and 0.001 mM salts of Co2+ and Ni2+, 0.001 mM salts of Cu2+, 0.001–10 mM boric acid, and 0.001–0.1 mM ammonium molybdate left phosphate uptake unaffected. 相似文献
15.
Douglas?J.?Kojetin Richele?J.?Thompson Linda?M.?Benson Stephen?Naylor Jenora?Waterman Keith?G.?Davies Charles?H.?Opperman Keith?Stephenson James?A.?Hoch John?Cavanagh
The presence of a divalent metal ion in a negatively charged aspartic acid pocket is essential for phosphorylation of response
regulator proteins. Here, we present metal binding studies of the Bacillus subtilis response regulator Spo0F using NMR and μESI-MS. NMR studies show that the divalent metals Ca2+, Mg2+ and Mn2+ primarily bind, as expected, in the Asp pocket phosphorylation site. However, identical studies with Cu2+ show distinct binding effects in three specific locations: (i) the Asp pocket, (ii) a grouping of charged residues at a site
opposite of the Asp pocket, and (iii) on the β4-α4 loop and the β5/α5 interface, particularly around and including H101. μESI-MS studies stoichiometrically confirm the NMR studies and demonstrate that most divalent metal ions bind to Spo0F primarily
in a 1:1 ratio. Again, in the case of Cu2+, multiple metal-bound species are observed. Subsequent experiments reveal that Mg2+ supports phosphotransfer between KinA and Spo0F, while Cu2+ fails to support KinA phosphotransfer. Additionally, the presence of Cu2+ at non-lethal concentrations in sporulation media for B. subtilis and the related organism Pasteuria penetrans was found to inhibit spore formation while continuing to permit vegetative growth. Depending on the type of divalent metal
ion present, in vitro phosphorylation of Spo0F by its cognate kinase KinA can be inhibited. 相似文献
16.
The effect of heavy metal cations on the mitochondrial ornithine/citrulline transporter was tested in proteoliposomes reconstituted
with the protein purified from rat liver. The transport activity was measured as [3H]ornithine uptake in proteoliposomes containing internal ornithine (ornithine/ornithine antiport mode) or as [3H]ornithine efflux in the absence of external substrate (ornithine/H+ transport mode). 0.1 mM Cu2+, Pb2+, Hg2+, Cd2+ and Zn2+ strongly inhibited (more than 85%) the antiport; whereas Mn2+, Co2+ and Ni2+ inhibited less efficiently (25, 47 and 69%, respectively). The IC50 values of the transporter for the different metal ions ranged from 0.71 to 350 μM. Co2+ and Ni2+ also inhibited the [3H]ornithine efflux whereas Cu2+, Pb2+, Hg2+, Cd2+ and Zn2+ stimulated the [3H]ornithine efflux. The stimulation of the [3H]ornithine efflux by Cu2+ and Cd2+ (as well as by Pb2+, Hg2+ and Zn2+) was not prevented by NEM and was reversed by DTE. These features indicated that the inhibition of the antiport was due to
the interaction of the Cu2+, Pb2+, Hg2+, Cd2+ and Zn2+ with a population of SH groups, of the transporter, responsible for the inhibition of the physiological function; whereas
the stimulation of [3H]ornithine efflux was due to the induction of a pore-like function of the transporter caused by interaction of cations with
a different population of SH groups. Differently, the inhibition of the ornithine transporter by Ni2+, Co2+ or Mn2+ was caused by interaction with the substrate binding site, as indicated by the competitive or mixed inhibition. 相似文献
17.
Highly emissive heterocyclic asparagine derivatives bearing a 1,3,4-thiadiazolyl unit at the side chain, functionalised with
electron donor or acceptor groups, were synthesised and evaluated as amino acid-based fluorimetric chemosensors for metal
cations, such as Cu2+, Zn2+, Co2+ and Ni2+. The results suggest that there is a strong interaction through the donor heteroatoms at the side chain of the various asparagine
derivatives, with high sensitivity towards Cu2+ in a ligand–metal complex with 1:2 stoichiometry. Association constants and detection limits for Cu2+ were calculated. The photophysical and metal ion sensing properties of these asparagine derivatives confirm their potential
as fluorimetric chemosensors and suggest that they can be suitable for incorporation into chemosensory peptidic frameworks. 相似文献
18.
Chymosin can specifically break down the Phe105–Met106 peptide bond of milk κ-casein to form insoluble para-κ-casein, resulting in milk coagulation, a process that is used in making cheese. In this study, in order to obtain an alternative
milk coagulant which is safe and efficient, and simultaneously can produce cheese with a good taste, bovine prochymosin B
was chosen and constitutively expressed to a high level in Pichia pastoris. The recombinant chymosin was expressed mainly as a secretory form, and it exhibited milk-clotting activity. It was purified
by ammonium sulfate fractionation, anion exchange, followed by cation exchange chromatography. A final yield of 24.2% was
obtained for the purified enzyme, which appeared as a single band in SDS–PAGE having a molecular mass of approximate 36 kDa.
Proteolysis assay showed that it specifically hydrolyzed κ-casein. It was stable at 25–50°C and had optimal activity at 37°C and pH 4.0. The activity of the recombinant chymosin was
activated by cations such as Mn2+, Fe3+, Mg2+ and Na+, but inhibited by K+, Co2+, Zn2+, Ni2+, and to a lesser extent by Cu2+. These results suggested that recombinant bovine chymosin is an acid milk coagulant, and it could be considered as a safe
and efficient enzyme suitable for use in cheese production. 相似文献
19.
Alternating poly(Glu-Leu) exhibits a random coilstructure in pure water at neutral pH. The addition of 0.5 equiv of Ca2+ induces a coil-to--sheet transitionand the addition of 0.15 equivof Fe3+ induces a coil-to--helixtransition. Conformational competition between thesetwo structures was studied by mixing preformed-sheets and -helices in differentproportions. Circular dichroism spectra clearly show that-sheets are favored at the expense of-helices in -sheet-rich mixtures. 相似文献
20.
I. C. Farcasanu M. Mizunuma D. Hirata T. Miyakawa 《Molecular & general genetics : MGG》1998,259(5):541-548
In a search for components involved in Mn2+ homeostasis in the budding yeast Saccharomyces cerevisiae, we isolated a mutant with modifications in Mn2+ transport. The mutation was found to be located in HIP1, a gene known to encode a high-affinity permease for histidine. The mutation, designated hip1–272, caused a frameshift that resulted in a stop codon at position 816 of the 1812-bp ORF. This mutation led to Mn2+ resistance, whereas the corresponding null mutation did not. Both hip1–272 cells and the null mutant exhibited low tolerance to divalent cations such as Co2+, Ni2+, Zn2+, and Cu2+. The Mn2+ phenotype was not influenced by supplementary histidine in either mutant, whereas the sensitivity to other divalent cations
was alleviated by the addition of histidine. The cellular Mn2+ content of the hip1–272 mutant was lower than that of wild type or null mutant, due to increased rates of Mn2+ efflux. We propose that Hip1p is involved in Mn2+ transport, carrying out a function related to Mn2+ export.
Received: 9 January 1998 / Accepted: 4 May 1998 相似文献