Yee Benjamin, Lafi Feras F, Oakley Brian, Staley James T, Fuerst John A
School of Molecular and Microbial Sciences, University of Queensland, Brisbane, Queensland 4072, Australia.
BMC Evol Biol. 2007 Mar 12;7:37. doi: 10.1186/1471-2148-7-37.
The origin and evolution of the homologous GTP-binding cytoskeletal proteins FtsZ typical of Bacteria and tubulin characteristic of eukaryotes is a major question in molecular evolutionary biology. Both FtsZ and tubulin are central to key cell biology processes--bacterial septation and cell division in the case of FtsZ and in the case of tubulins the function of microtubules necessary for mitosis and other key cytoskeleton-dependent processes in eukaryotes. The origin of tubulin in particular is of significance to models for eukaryote origins. Most members of domain Bacteria possess FtsZ, but bacteria in genus Prosthecobacter of the phylum Verrucomicrobia form a key exception, possessing tubulin homologs BtubA and BtubB. It is therefore of interest to know whether other members of phylum Verrucomicrobia possess FtsZ or tubulin as their FtsZ-tubulin gene family representative.
Verrucomicrobium spinosum, a member of Phylum Verrucomicrobia of domain Bacteria, has been found to possess a gene for a protein homologous to the cytoskeletal protein FtsZ. The deduced amino acid sequence has sequence signatures and predicted secondary structure characteristic for FtsZ rather than tubulin, but phylogenetic trees and sequence analysis indicate that it is divergent from all other known FtsZ sequences in members of domain Bacteria. The FtsZ gene of V. spinosum is located within a dcw gene cluster exhibiting gene order conservation known to contribute to the divisome in other Bacteria and comparable to these clusters in other Bacteria, suggesting a similar functional role.
Verrucomicrobium spinosum has been found to possess a gene for a protein homologous to the cytoskeletal protein FtsZ. The results suggest the functional as well as structural homology of the V. spinosum FtsZ to the FtsZs of other Bacteria implying its involvement in cell septum formation during division. Thus, both bacteria-like FtsZ and eukaryote-like tubulin cytoskeletal homologs occur in different species of the phylum Verrucomicrobia of domain Bacteria, a result with potential major implications for understanding evolution of tubulin-like cytoskeletal proteins and the origin of eukaryote tubulins.
同源的GTP结合细胞骨架蛋白细菌特有的FtsZ和真核生物特有的微管蛋白的起源与进化是分子进化生物学中的一个主要问题。FtsZ和微管蛋白对于关键的细胞生物学过程都至关重要——FtsZ参与细菌隔膜形成和细胞分裂，而微管蛋白对于真核生物有丝分裂及其他关键的细胞骨架依赖性过程所必需的微管功能至关重要。特别是微管蛋白的起源对于真核生物起源模型具有重要意义。细菌域的大多数成员都拥有FtsZ，但疣微菌门Prosthecobacter属的细菌是一个关键例外，它们拥有微管蛋白同源物BtubA和BtubB。因此，了解疣微菌门的其他成员是否拥有FtsZ或微管蛋白作为其FtsZ - 微管蛋白基因家族代表很有意义。
已发现细菌域疣微菌门的成员棘状疣微菌拥有一个与细胞骨架蛋白FtsZ同源的蛋白质基因。推导的氨基酸序列具有FtsZ而非微管蛋白的序列特征和预测的二级结构特征，但系统发育树和序列分析表明它与细菌域成员中所有其他已知的FtsZ序列不同。棘状疣微菌的FtsZ基因位于一个dcw基因簇内，该基因簇表现出已知有助于其他细菌中分裂体的基因顺序保守性，并且与其他细菌中的这些基因簇相当，表明其功能相似。
已发现棘状疣微菌拥有一个与细胞骨架蛋白FtsZ同源的蛋白质基因。结果表明棘状疣微菌FtsZ与其他细菌的FtsZ在功能以及结构上具有同源性，这意味着它参与分裂过程中的细胞隔膜形成。因此，细菌样的FtsZ和真核生物样的微管蛋白细胞骨架同源物存在于细菌域疣微菌门的不同物种中，这一结果对于理解微管蛋白样细胞骨架蛋白的进化和真核生物微管蛋白的起源可能具有重大意义。
