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11.
The amino acid sequences of 47 P-type ATPases from several eukaryotic and bacterial kingdoms were divided into three structural segments based on individual hydropathy profiles. Each homologous segment was (1) multiply aligned and functionally evaluated, (2) statistically analyzed to determine the degrees of sequence similarity, and (3) used for the construction of parsimonious phylogenetic trees. The results show that all of the P-type ATPases analyzed comprise a single family with four major clusters correlating with their cation specificities and biological sources as follows: cluster 1: Ca2+-transporting ATPases; cluster 2: Na+- and gastric H+-ATPases; cluster 3: plasma membrane H+-translocating ATPases of plants, fungi, and lower eukaryotes; and cluster 4: all but one of the bacterial P-type ATPases (specific for K+, Cd2+, Cu2+ and an unknown cation). The one bacterial exception to this general pattern was the Mg2+-ATPase of Salmonella typhimurium, which clustered with the eukaryotic sequences. Although exceptions were noted, the similarities of the phylogenetic trees derived from the three segments analyzed led to the probability that the N-terminal segments 1 and the centrally localized segments 2 evolved from a single primordial ATPase which existed prior to the divergence of eukaryotes from prokaryotes. By contrast, the C-terminal segments 3 appear to be eukaryotic specific, are not found in similar form in any of the prokaryotic enzymes, and are not all demonstrably homologous among the eukaryotic enzymes. These C-terminal domains may therefore have either arisen after the divergence of eukaryotes from prokaryotes or exhibited more rapid sequence divergence than either segment 1 or 2, thus masking their common origin. The relative rates of evolutionary divergence for the three segments were determined to be segment 2 < segment 1 < segment 3. Correlative functional analyses of the most conserved regions of these ATPases, based on published site-specific mutagenesis data, provided preliminary evidence for their functional roles in the transport mechanism. Our studies define the structural and evolutionary relationships among the P-type ATPases. They should provide a guide for the design of future studies of structure-function relationships employing molecular genetic, biochemical, and biophysical techniques.
Correspondence to: M.H. Saier, Jr. 相似文献
12.
Piotr Ceglowski Alexander Boitsov Natalia Karamyan Sunghee Chai Juan C. Alonso 《Molecular & general genetics : MGG》1993,241(5-6):579-585
The low-copy-number and broad-host-range pSM19035-derived plasmid pBT233 is stably inherited in Bacillus subtilis cells. Two distinct regions, segA and segB, enhance the segregational stability of the plasmid. Both regions function in a replicon-independent manner. The maximization of random plasmid segregation is accomplished by the recombination proficiency of the host or the presence of the pBT233 segA region. The segA region contains two open reading frames (or) [ and ]. Inactivation or deletion of or results in SegA– plasmids. Better than random segregation requires an active segB region. The segB region contains two ors (or and or). Inactivation of either of the orfs does not lead to an increase in cell death, but or– plasmids are randomly segregated. These results suggest that pBT233 stabilization relies on a complex system involving resolution of plasmid oligomers (segA) and on the function(s) encoded by the segB region. 相似文献
13.
István Papp László Dorgai Péter Papp Erzsébet Jónás Ferenc Olasz László Orosz 《Molecular & general genetics : MGG》1993,240(2):258-264
Bacteriophage 16-3 inserts its genome into the chromosome of Rhizobium meliloti strain 41 (Rm41) by site-specific recombination. The DNA regions around the bacterial attachment site (attB) and one of the hybrid attachment sites bordering the integrated prophage (attL) were cloned and their nucleotide sequences determined. We demonstrated that the 51 by region, where the phage and bacterial DNA sequences are identical, is active as a target site for phage integration. Furthermore it overlaps the 3 end of a putative proline tRNA gene. This gene shows 79% similartiy to the corresponding proline tRNA-like genomic target sequence of certain integrative plasmids in Actinomycetes. 相似文献
14.
R. J. Leer H. Christiaens W. Verstraete L. Peters M. Posno P. H. Pouwels 《Molecular & general genetics : MGG》1993,239(1-2):269-272
A chloramphenicol-resistance gene (cml) was introduced into the Lactobacillus plantarum gene encoding conjugated bile acid hydrolasc (cbh) on a ColEl replicon. This plasmid which is nonreplicative in Lactobacillus was used to transform L. plantarum strain 80. A homologous double cross-over recombination event resulted in replacement of the chromosomal cbh gene by the cml-containing cbh gene. The transformants obtained were unable to synthesize active conjugated bile acid hydrolase (Cbh). The Cbh-CmlR phenotype was stably maintained for more than 100 generations under nonselective conditions.This paper is dedicated with great appreciation to Dr. Frits Berends on the occasion of his retirement as Head of the Biochemistry Department of the TNO Medical Biological Laboratory 相似文献
15.
药敏药片经临床对金黄色葡萄球菌、大肠埃希氏菌、铜绿假单胞菌等235株考核.表明药片工艺研究先进,药片与培养基结合牢固,无断裂、崩解,不渗出颗粒,抑菌圈呈同心园扩散.边缘清楚。药物含量均匀,释放度好。药片抑菌差仅1~3mm;而纸片抑菌差为2~12mm。药片变黑系数CV为2.71~4.21;而纸片CV为3.82~14.36。表明纸片片间差大,药片精密度明显好于纸片。 相似文献
16.
A model of the C
3 photosynthetic system is developed which describes the sensitivity of the steadystate rate of carbon dioxide assimilation to changes in the activity of several enzymes of the system. The model requires measurements of the steady-state rate of carbon dioxide assimilation, the concentrations of several intermediates in the photosynthetic system, and the concentration of the active site of ribulose 1,5-bisphosphate carboxyalse/oxygenase (Rubisco). It is shown that in sunflowers (Helianthus annuus L.) at photon flux densities that are largely saturating for the rate of photosynthesis, the steady-stete rate of carbon dioxide assimilation is most sensitive to Rubisco activity and, to a lesser degree, to the activities of the stromal fructose, 6-bisphosphatase and the enzymes catalysing sucrose synthesis. The activities of sedoheptulose 1,7-bisphosphatase, ribulose 5-phosphate kinase, ATP synthase and the ADP-glucose pyrophosphorylase are calculated to have a negligible effect on the flux under the high-light conditions. The utility of this analysis in developing simpler models of photosynthesis is also discussed.Abbreviations
c
i
intercellular CO2 concentration
-
C
infP
supJ
control coefficient for enzyme P with respect to flux J
- DHAP
dihydroxyacetonephosphate
- E4P
erythrose 4-phosphate
- F6P
fructose 6-phosphate
- FBP
fructose 1,6-bisphosphate
- FBPase
fructose 1,6-bisphosphatase
- G3P
glyceraldehyde 3-phosphate
- G1P
glucose 1-phosphate
- G6P
glucose 6-phosphate
- Pi
inorganic phosphate
- PCR
photosynthetic carbon reduction
- PGA
3-phosphoglyceric acid
- PPFD
photosynthetically active photon flux density
-
R
n
J
response coefficient for effector n with respect to flux J
- R5P
ribose 5-phosphate
- Rubisco
ribulose 1,5-bisphosphate carboxylase/oxygenase
- Ru5P
ribulose 5-phosphate
- RuBP
ribulose 1,5-bisphosphate
- S7P
sedoheptulose 7-phosphate
- SBP
sedoheptulose 1,7-bisphosphate
- SBPase
sedoheptulose 1,7-bisphosphatase
- SPS
sucrose-phosphate synthase
- Xu5P
xylulose 5-phosphate
-
n
P
elasticity coefficient for effector n with respect to the catalytic velocity of enzyme P
This research was funded by an Australian Research Council grant to I.E.W. and was undertaken during a visity by K.A.M. to the James Cook University of North Queensland. The expert help of Glenys Hanley and Mick Kelly is greatly appreciated. 相似文献
17.
Abstract The precise molecular mechanism of Staphylococcus aureus β -toxin inactivation by the serotype F triple-converting phage φ42, φA1 and φA3 was investigated. Sequence analysis of the φ42 ( attP ) and Staphylococcus aureus ( attB ) attachment sites and the left ( attL ) and right ( attR ) chromosomal/bacteriophage DNA junctions of individual lysogens, each harbouring a triple-converting phage, revealed the presence of a common 14-bp core sequence in all four sites. These findings indicate that the genomes of the triple-converting phage integrate into the 5'-end of the β-toxin gene ( hlb ) by a site- and orientation-specific mechanism identical to that previously described for the serotype F double-converting phage φ13. 相似文献
18.
摘要 目的:探讨血清肿瘤异常蛋白(TAP)、三叶因子3(TFF3)与晚期胃癌患者应用含奥沙利铂化疗方案敏感性和预后的关系。方法:选择2017年1月至2020年1月河北大学附属医院收治的115例晚期胃癌患者,所有患者接受含奥沙利铂化疗方案治疗,根据疗效分为敏感组(47例)和耐药组(68例)。化疗前检测血清TAP、TFF3水平,受试者工作特征(ROC)曲线分析TAP、TFF3预测晚期胃癌患者接受含奥沙利铂化疗疗效的价值。治疗后随访,Wilcoxon检验不同血清TAP、TFF3表达下晚期胃癌患者中位OS时间差异。结果:耐药组血清TAP、TFF3水平高于敏感组(P<0.05)。TAP、TFF3预测晚期胃癌患者含奥沙利铂化疗耐药的曲线下面积分别为0.717、0.690,联合TAP和TFF3预测晚期胃癌患者含奥沙利铂化疗耐药的曲线下面积为0.801,高于单独TAP、TFF3单独检测。随访期间失访2例,死亡54例,高水平TAP、高水平TFF3晚期胃癌患者中位OS时间短于低水平TAP、低水平TFF3晚期胃癌患者(P<0.05)。结论:对含奥沙利铂化疗耐药的晚期胃癌患者血清TAP、TFF3水平显著增高,高水平TAP、TFF3晚期胃癌患者中位OS时间较短,联合检测血清TAP和TFF3可预测晚期胃癌患者化疗反应性和预后。 相似文献
19.
Thylakoids of Oscillatoria chalybea are able to split water. The Hill reaction of these thylakoids is sensitive to DCMU. Diphenylcarbazide can substitute for water as the electron donor to photosystem II with these fully functioning thylakoids. However, the diphenylcarbazide photooxidation is completely insensitive to 3-(3,4-dichlorophenyl)-N-N-dimethyl urea (DCMU) at high diphenylcarbazide concentrations. In with Tris-treated Oscillatoria thylakoids the water splitting capacity is lost and diphenylcarbazide restores electron transport through photosystem II as occurs with higher plant chloroplasts. However, also these photoreactions are insensitive to DCMU. If diphenylcarbazide acts in Oscillatoria as an electron donor to photosystem II the result suggests that diphenylcarbazide feeds in its electrons behind the DCMU inhibition site. This in turn indicates that in Oscillatoria the site of inhibition of DCMU is on the donor side of photosystem II.Abbreviations Used DCMU
3-(3,4-dichlorophenyl)-N-N-dimethyl urea
- DPC
diphenylcarbazide
- DCPiP
2,6-dichlorophenol indophenol
- TMB
tetramethyl benzidine
- A-2-sulf
anthraquinone-2-sulfonate 相似文献
20.