Structure-function relationships of two paralogous single-stranded DNA-binding proteins from Streptomyces coelicolor: implication of SsbB in chromosome segregation during sporulation.
Structure-function relationships of two paralogous single-stranded DNA-binding proteins from Streptomyces coelicolor: implication of SsbB in chromosome segregation during sporulation.
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DOI：
10.1093/nar/gkt050
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发表时间：
2013-04-01
影响因子：
14.9
通讯作者：
Vujaklija D
中科院分区：
文献类型：
--
作者：
Paradzik T;Ivic N;Filic Z;Manjasetty BA;Herron P;Luic M;Vujaklija D
色链霉菌的线性染色体包含两个平行的ssb基因，ssbA和ssbB。通过突变分析，我们得出结论，ssbA是必不可少的，而ssbB在孢子形成过程中对染色体分离起关键作用。在ssbB突变体中，约30%的孢子缺乏DNA。两种ssb基因表达不同；在极少量培养基中，两个基因的表达均延长，而ssbB基因的表达显著上调。ssbA基因作为多顺反子mRNA的一部分，在rpsF翻译起始密码子上游163 bp和75 bp两个起始位点转录。ssbB基因转录为单顺反子mRNA，来自AUG密码子上游73 bp的一个不寻常的启动子区域。通过色氨酸荧光猝灭和电泳迁移位移监测单链dna结合蛋白的独特dna结合亲和力。在1.7 Å分辨率下，SsbB的晶体结构显示出常见的OB-fold，缺乏SsbA中保守的钳状结构和以前未发表的a /B和C/D亚基之间的S-S桥。这是首次报道从同一生物中测定同源单链dna结合蛋白结构。系统发育分析显示，放线菌中ssb基因经常重复，而它们的强保留表明它们参与了重要的细胞功能。
The linear chromosome of Streptomyces coelicolor contains two paralogous ssb genes, ssbA and ssbB. Following mutational analysis, we concluded that ssbA is essential, whereas ssbB plays a key role in chromosome segregation during sporulation. In the ssbB mutant, ∼30% of spores lacked DNA. The two ssb genes were expressed differently; in minimal medium, gene expression was prolonged for both genes and significantly upregulated for ssbB. The ssbA gene is transcribed as part of a polycistronic mRNA from two initiation sites, 163 bp and 75 bp upstream of the rpsF translational start codon. The ssbB gene is transcribed as a monocistronic mRNA, from an unusual promoter region, 73 bp upstream of the AUG codon. Distinctive DNA-binding affinities of single-stranded DNA-binding proteins monitored by tryptophan fluorescent quenching and electrophoretic mobility shift were observed. The crystal structure of SsbB at 1.7 Å resolution revealed a common OB-fold, lack of the clamp-like structure conserved in SsbA and previously unpublished S-S bridges between the A/B and C/D subunits. This is the first report of the determination of paralogous single-stranded DNA-binding protein structures from the same organism. Phylogenetic analysis revealed frequent duplication of ssb genes in Actinobacteria, whereas their strong retention suggests that they are involved in important cellular functions.
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影响因子：
3.2
作者：
Ainsa, JA;Ryding, NJ;Chater, KF
通讯作者：
Chater, KF
影响因子：
3.5
作者：
CHEREPANOV, PP;WACKERNAGEL, W
通讯作者：
WACKERNAGEL, W
影响因子：
3.2
作者：
Jakimowicz, D;Mouz, S;Chater, KF
通讯作者：
Chater, KF
影响因子：
3.2
作者：
Dedrick, Rebekah M.;Wildschutte, Hans;McCormick, Joseph R.
通讯作者：
McCormick, Joseph R.
DOI：
10.1107/s0907444904019158
发表时间：
2004-12-01
影响因子：
2.2
作者：
Emsley, P;Cowtan, K
通讯作者：
Cowtan, K