Derman Alan I, Becker Eric C, Truong Bao D, Fujioka Akina, Tucey Timothy M, Erb Marcella L, Patterson Paula C, Pogliano Joe
Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093-0377, USA.
Mol Microbiol. 2009 Aug;73(4):534-52. doi: 10.1111/j.1365-2958.2009.06771.x. Epub 2009 Jul 7.
Actin, one of the most abundant proteins in the eukaryotic cell, also has an abundance of relatives in the eukaryotic proteome. To date though, only five families of actins have been characterized in bacteria. We have conducted a phylogenetic search and uncovered more than 35 highly divergent families of actin-like proteins (Alps) in bacteria. Their genes are found primarily on phage genomes, on plasmids and on integrating conjugative elements, and are likely to be involved in a variety of functions. We characterize three Alps and find that all form filaments in the cell. The filaments of Alp7A, a plasmid partitioning protein and one of the most divergent of the Alps, display dynamic instability and also treadmill. Alp7A requires other elements from the plasmid to assemble into dynamic polymers in the cell. Our findings suggest that most if not all of the Alps are indeed actin relatives, and that actin is very well represented in bacteria.
肌动蛋白是真核细胞中最丰富的蛋白质之一，在真核生物蛋白质组中也有大量的同源物。然而，迄今为止，细菌中仅鉴定出五个肌动蛋白家族。我们进行了系统发育搜索，在细菌中发现了35多个高度分化的肌动蛋白样蛋白（Alps）家族。它们的基因主要存在于噬菌体基因组、质粒和整合接合元件上，可能参与多种功能。我们对三种Alps进行了表征，发现它们在细胞中均能形成细丝。Alp7A是一种质粒分配蛋白，也是Alps中最具分化性的蛋白之一，其细丝表现出动态不稳定性且存在踏车行为。Alp7A需要质粒中的其他元件才能在细胞中组装成动态聚合物。我们的研究结果表明，大多数（如果不是全部的话）Alps确实是肌动蛋白的同源物，并且细菌中肌动蛋白的代表性非常好。
