Morcinek-Orłowska Joanna, Galińska Justyna, Glinkowska Monika Katarzyna
Department of Bacterial Molecular Genetics, University of Gdansk, Gdańsk, Poland.
Acta Biochim Pol. 2019 Apr 10;66(2):139-146. doi: 10.18388/abp.2018_2798.
Bacterial cells often inhabit environments where conditions can change rapidly. Therefore, a lot of bacterial species developed control strategies allowing them to grow and divide very fast during feast and slow down both parameters during famine. Under rich nutritional conditions, fast-growing bacteria can divide with time interval equal to half of the period required to synthesize their chromosomes. This is possible due to multifork replication which allows ancestor cells to start copying genetic material for their descendants. This reproduction scheme was most likely selected for, since it enables maximization of growth rate and hence - effective competition for resources, while ensuring that DNA replication will not become limiting for cell division. Even with this complexity of cell cycle, isogenic bacterial cells grown under defined conditions display remarkably narrow distribution of sizes. This may suggest that mechanisms exists to control cell size at division step. Alternative view, with great support in experimental data is that the only step coordinated with cell growth is the initiation of DNA replication. Despite decades of research we are still not sure what the driving forces in bacterial cell cycle are. In this work we review recent advances in understanding coordination of growth with DNA replication coming from single cell studies and systems biology approaches.
细菌细胞常常栖息于条件会迅速变化的环境中。因此，许多细菌物种形成了调控策略，使它们在营养丰富时能够快速生长和分裂，而在营养匮乏时减缓这两个参数。在营养丰富的条件下，快速生长的细菌能够以等于合成其染色体所需时间一半的时间间隔进行分裂。这之所以可能，是因为多叉复制，它允许亲代细胞开始为其后代复制遗传物质。这种繁殖方式很可能是经过选择的，因为它能够使生长速率最大化，从而有效地竞争资源，同时确保DNA复制不会成为细胞分裂的限制因素。即使细胞周期如此复杂，在特定条件下生长的同基因细菌细胞的大小分布仍非常狭窄。这可能表明存在控制分裂时细胞大小的机制。另一种在实验数据中有大量支持的观点是，唯一与细胞生长协调的步骤是DNA复制的起始。尽管经过了数十年的研究，我们仍然不确定细菌细胞周期的驱动力是什么。在这项工作中，我们回顾了来自单细胞研究和系统生物学方法的在理解生长与DNA复制协调方面的最新进展。
