Characterization of the cys gene locus from Allochromatium vinosum indicates an unusual sulfate assimilation pathway*
Characterization of the cys gene locus from Allochromatium vinosum indicates an unusual sulfate assimilation pathway*
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DOI：
10.1023/a:1007058421714
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发表时间：
2000-03
影响因子：
2.8
通讯作者：
S. Neumann;A. Wynen;H. G. Trüper;C. Dahl
中科院分区：
文献类型：
--
作者：
S. Neumann;A. Wynen;H. G. Trüper;C. Dahl
在光合紫色硫细菌Allochromatium vinosum（以前称为Chromatium vinosum）的基因组中鉴定了基因cysB、cysI、cysH、cysD、cysN和selD的同源物。基于氨基酸比较，这些基因编码铁氧还蛋白依赖性西罗血红素-亚硫酸盐还原酶（Cysl），不含硫氧还蛋白结构域（CysH）的植物型同化APS还原酶，异二聚体ATP硫酸化酶（CysDN）的两个不同亚基，转录调节因子（CysB）和硒磷酸合酶（SelD）cysIHDN似乎形成一个操纵子，cysB位于其前面，cysB的转录方向与cysIHDN相反，SelD位于cysN的下游，与cysIHDN的转录方向不同。APS激酶基因的缺失和同化性APS还原酶基因的存在意味着A. vinosum沿着高等植物所建议的途径沿着进行，而没有PAPS的中间形成。两个完全独立的途径，涉及专门的酶是用于同化硫酸盐还原和异化硫氧化在A。vinosum。cysB的存在表明同化硫酸盐还原基因仅在不存在还原硫化合物的情况下表达。
Homologues of the genescysB, cysl, cysH, cysD, cysN, andselDwere identified in the genome of the phototrophic purple sulfur bacteriumAllochromatium vinosum(formerlyChromatium vinosum). On the basis of amino acid comparisons these genes encode a ferredoxin-dependent siroheme-sulfite reductase (Cysl), a plant-type assimilatory APS reductase without thioredoxin domain (CysH), the two different subunits of heterodimeric ATP sulfurylase (CysDN), a transcriptional regulator (CysB) and a selenophosphate synthase (SelD).cysIHDNappear to form an operon and are preceded bycysBwhich is transcribed in the opposite direction.SelDis situated downstream ofcysNand transcribed divergently tocysIHDN. The lack of a gene for APS kinase and presence of a gene for an assimilatory APS reductase implies that assimilatory sulfate reduction inA. vinosumproceeds along the pathway suggested for higher plants without intermediary formation of PAPS. Two completely separate pathways involving specialized enzymes are used for assimilatory sulfate reduction and dissimilatory sulfur oxidation inA. vinosum. The presence ofcysBindicates that the genes for assimilatory sulfate reduction are expressed only in the absence of reduced sulfur compounds.