Importance of Proteins Controlling Initiation of DNA Replication in the Growth of the High-Pressure-Loving Bacterium Photobacterium profundum SS9
Importance of Proteins Controlling Initiation of DNA Replication in the Growth of the High-Pressure-Loving Bacterium Photobacterium profundum SS9
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DOI：
10.1128/jb.00576-09
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发表时间：
2009-10-15
影响因子：
3.2
通讯作者：
Ferguson, Gail P.
中科院分区：
文献类型：
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作者：
El-Hajj, Ziad W.;Tryfona, Theodora;Ferguson, Gail P.
深海细菌在低温高静水压力下最佳生长的分子机制(S)尚不清楚。为了进一步了解这一机制(S)，先前的一项研究筛选了深海细菌深光杆菌SS9的转座子突变体库，并鉴定了在高压下相对于亲本菌株的生长发生变化的突变株。其中两个突变体Fl23(PBPRA3229：：mini-Tn10)和Fl28(PBPRA1039：：mini-Tn10)分别具有高压敏感性和生长促进表型。PBPRA3229和PBPRA1039基因编码的蛋白质分别与大肠杆菌DiaA和SEQA高度相似，分别是启动DNA复制的正调控因子和负调控因子。在本研究中，我们研究了PBPRA3229和PBPRA1039分别编码DIAA和SEQA同源物的假设。与此一致，我们确定携带质粒的PBPRA3229和PBPRA1039基因分别与缺乏DiaA和SEQA的大肠杆菌突变体的DNA复制开始恢复同步。此外，PBPRA3229恢复了大肠杆菌Dna A(Cs)DiaA双突变株的冷敏感性表型，而PBPRA1039抑制了大肠杆菌Dna A(Cs)单突变株的冷敏感性表型。综上所述，这些发现表明，在FL23和FL28中被破坏的基因分别编码DiaA和SEQA同源物。因此，我们的发现支持了一个模型，即高压影响深源假单胞菌SS9中DNA复制的启动，并且在这些条件下，正调控因子(DIAA)的存在或负调控因子(SEQA)的去除都会促进生长。
The molecular mechanism(s) by which deep-sea bacteria grow optimally under high hydrostatic pressure at low temperatures is poorly understood. To gain further insight into the mechanism(s), a previous study screened transposon mutant libraries of the deep-sea bacterium Photobacterium profundum SS9 and identified mutants which exhibited alterations in growth at high pressure relative to that of the parent strain. Two of these mutants, FL23 (PBPRA3229::mini-Tn10) and FL28 (PBPRA1039::mini-Tn10), were found to have high-pressure sensitivity and enhanced-growth phenotypes, respectively. The PBPRA3229 and PBPRA1039 genes encode proteins which are highly similar to Escherichia coli DiaA, a positive regulator, and SeqA, a negative regulator, respectively, of the initiation of DNA replication. In this study, we investigated the hypothesis that PBPRA3229 and PBPRA1039 encode DiaA and SeqA homologs, respectively. Consistent with this, we determined that the plasmid-carried PBPRA3229 and PBPRA1039 genes restored synchrony to the initiation of DNA replication in E. coli mutants lacking DiaA and SeqA, respectively. Additionally, PBPRA3229 restored the cold sensitivity phenotype of an E. coli dnaA(Cs) diaA double mutant whereas PBPRA1039 suppressed the cold sensitivity phenotype of an E. coli dnaA(Cs) single mutant. Taken together, these findings show that the genes disrupted in FL23 and FL28 encode DiaA and SeqA homologs, respectively. Consequently, our findings add support to a model whereby high pressure affects the initiation of DNA replication in P. profundum SS9 and either the presence of a positive regulator (DiaA) or the removal of a negative regulator (SeqA) promotes growth under these conditions.