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171.
A gene for a putative two-component histidine kinase, which is homologous to os-1 from Neurospora crassa, was cloned and sequenced from the plant-pathogenic fungus Cochliobolus heterostrophus. The predicted protein possessed the conserved histidine kinase domain, the response regulator domain, and six tandem repeats of 92-amino-acids at the N-terminal end that are found in histidine kinases from other filamentous fungi. Introduction of the histidine kinase gene complemented the deficiency of the C. heterostrophus dic1 mutant, suggesting that the Dic1 gene product is a histidine kinase. Dic1 mutants are resistant to dicarboximide and phenylpyrrole fungicides, and they are sensitive to osmotic stress. We previously classified dic1 alleles into three types, based on their phenotypes. To explain the phenotypic differences among the dic1 mutant alleles, we cloned and sequenced the mutant dic1 genes and compared their sequences with that of the wild-type strain. Null mutants for Dic1, and mutants with a deletion or point mutation in the N-terminal repeat region, were highly sensitive to osmotic stress and highly resistant to both fungicides. A single amino acid change within the kinase domain or the regulator domain altered the sensitivity to osmotic stress and conferred moderate resistance to the fungicides. These results suggest that this predicted protein, especially its repeat region, has an important function in osmotic adaptation and fungicide resistance.Communicated by C. A. M. J. J. van den Hondel 相似文献
172.
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174.
During a survey of two-component system genes, a list of neighboring histidine kinase and response regulator genes, encoded
on the same strand, was compiled from over 200 fully sequenced bacteria. It was observed that many gene pairs overlapped,
and although such overlaps can potentially occur in two phases (relative reading frames), one phase predominated for overlaps
of seven or more nucleotides. Preference for a particular phase cannot be explained by arguments of sequence restraint (mutations
in one gene differentially affect an overlapping gene, depending on phase). We have therefore investigated a potential explanation
of the observed phase bias. For phase +1 gene overlaps, simulated point mutations in the overlapping region result in more
severe changes to the downstream gene product than to the upstream gene product; vice versa in phase +2. Additionally, codon
usage frequencies in nonoverlapping regions are more similar to those at the end of the upstream gene than the beginning of
the downstream gene in overlaps. Taking both observations together, we propose that new gene overlaps generally arise by N-terminal
extension of a downstream gene, creating a novel sequence at the start of the downstream gene. Sequence changes in this newly
coding sequence will alter the sequences of both the new and the original coding sequence (the C-terminal region of the upstream
gene). However, these changes will be less detrimental to the original coding sequence if the two genes overlap in phase +1,
leading to selective retention during evolution of phase +1 overlaps relative to phase +2 overlaps.
Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Supplementary Information: The gene list and overlap dataset can be downloaded from the journal’s web site
().
[Reviewing Editor: Dr. Hector Musto] 相似文献
175.
We recently reported that a histidine (H191) in the S3-S4 loop of domain I is critical for nickel inhibition of the Cav3.2 T-type Ca2+ channel. As in Cav3.2, two histidine residues are commonly found in the IS3-IS4 loops of mammalian Cav2.3 Ca2+ channels, which are also blocked by low micromolar concentrations of nickel. We show here by site-directed mutagenesis and electrophysiology that both residues contribute to the nickel sensitivity of Cav2.3, with H183 being more critical than H179. These findings strongly suggest that both H179 and H183 in the IS3-IS4 loop are essential structural determinants required for nickel sensitive inhibition of the Cav2.3. 相似文献
176.
Kefala G Kwiatkowski W Esquivies L Maslennikov I Choe S 《Journal of structural and functional genomics》2007,8(4):167-172
Integral membrane proteins have become the focus of interest of many laboratories and structural genomics consortia, but their
study is hampered by bottlenecks in production, solubilization, purification and crystallization. In our laboratory we have
addressed the problem of high-level protein expression in the membrane of Escherichia coli by use of Mistic, a novel Bacillus subtilis protein, as a fusion partner. In this study we examine the effect of Mistic on protein expression and membrane integration
levels of members of the E. coli histidine kinase receptor family. We find that Mistic fusion invariably increases the overall yield by targeting the cargo
proteins more efficiently to the membrane and may even replace the signal sequence. Mistic fusion methods will likely be instrumental
for high-level expression of other integral membrane proteins. 相似文献
177.
Karena L. Waller Lisa M. Stubberfield Valentina Dubljevic Xuili An Narla Mohandas Ross L. Coppel 《生物化学与生物物理学报:生物膜》2007,1768(9):2145-2156
Plasmodium falciparum parasites express and traffick numerous proteins into the red blood cell (RBC), where some associate specifically with the membrane skeleton. Importantly, these interactions underlie the major alterations to the modified structural and functional properties of the parasite-infected RBC. P. falciparum Erythrocyte Membrane Protein 3 (PfEMP3) is one such parasite protein that is found in association with the membrane skeleton. Using recombinant PfEMP3 proteins in vitro, we have identified the region of PfEMP3 that binds to the RBC membrane skeleton, specifically to spectrin and actin. Kinetic studies revealed that residues 38-97 of PfEMP3 bound to purified spectrin with moderately high affinity (KD(kin) = 8.5 × 10− 8 M). Subsequent deletion mapping analysis further defined the binding domain to a 14-residue sequence (IFEIRLKRSLAQVL; KD(kin) = 3.8 × 10− 7 M). Interestingly, this same domain also bound to F-actin in a specific and saturable manner. These interactions are of physiological relevance as evidenced by the binding of this region to the membrane skeleton of inside-out RBCs and when introduced into resealed RBCs. Identification of a 14-residue region of PfEMP3 that binds to both spectrin and actin provides insight into the potential function of PfEMP3 in P. falciparum-infected RBCs. 相似文献
178.
Changes in the amino acid pool in a nickel-resistant strain of Saccharomyces cerevisiae 总被引:1,自引:0,他引:1
Masanori Joho Yuichi Imada Hiroshi Tohoyama Tetsuo Murayama 《FEMS microbiology letters》1988,55(2):137-140
In a Ni-resistant strain of S. cerevisiae , the histidine content of the amino acid pool was increased by culture in a Ni-supplemented medium, while the content of other amino acids was decreased. The toxicity of nickel to yeast was reduced by addition of histidine to the medium. It is concluded that histidine content plays an important role in Ni-resistance in yeast. 相似文献
179.
Focus on phosphohistidine 总被引:1,自引:0,他引:1
Summary. Phosphohistidine has been identified as an enzymic intermediate in numerous biochemical reactions and plays a functional role
in many regulatory pathways. Unlike the phosphoester bond of its cousins (phosphoserine, phosphothreonine and phosphotyrosine),
the phosphoramidate (P–N) bond of phosphohistidine has a high ΔG° of hydrolysis and is unstable under acidic conditions. This
acid-lability has meant that the study of protein histidine phosphorylation and the associated protein kinases has been slower
to progress than other protein phosphorylation studies.
Histidine phosphorylation is a crucial component of cell signalling in prokaryotes and lower eukaryotes. It is also now becoming
widely reported in mammalian signalling pathways and implicated in certain human disease states. This review covers the chemistry
of phosphohistidine in terms of its isomeric forms and chemical derivatives, how they can be synthesized, purified, identified
and the relative stabilities of each of these forms. Furthermore, we highlight how this chemistry relates to the role of phosphohistidine
in its various biological functions. 相似文献
180.
Iris Stallkamp William Dowhan Karlheinz Altendorf K. Jung 《Archives of microbiology》1999,172(5):295-302
Synthesis of the high-affinity K+-translocating Kdp-ATPase of Escherichia coli, encoded by the kdpFABC operon, is regulated by the membrane-bound sensor kinase KdpD and the soluble response regulator KdpE. K+ limitation or a sudden increase in osmolarity induces the expression of kdpFABC. Due to the importance of K+ to maintain turgor, it has been proposed that KdpD is a turgor sensor. Although the primary stimulus that KdpD senses is
unknown, alterations in membrane strain or the interaction between KdpD and membrane components might be good candidates.
Here, we report a study of the influence of the membrane phospholipid composition on the function of KdpD in vivo and in vitro
using various E. coli mutants defective in phospholipid biosynthesis. Surprisingly, neither the lack of the major E. coli phospholipid phosphatidylethanolamine nor the drastic reduction of the phosphatidylglycerol/cardiolipin content influenced
induction of kdpFABC expression significantly. However, in vitro reconstitution experiments with synthetic phospholipids clearly demonstrated
that KdpD kinase activity is dependent on negatively charged phospholipids, whereas the structure of the phospholipids plays
a minor role. These results indicate that electrostatic interactions are important for the activity of KdpD.
Received: 29 March 1999 / Accepted: 26 July 1999 相似文献