Mechanisms of bacterial morphogenesis: Evolutionary cell biology approaches provide new insights

Abstract

How Darwin’s “endless forms most beautiful” have evolved remains one of the most exciting questions in biology. The significant variety of bacterial shapes is most likely due to the specific advantages they confer with respect to the diverse environments they occupy. While our understanding of the mechanisms generating relatively simple shapes has improved tremendously in the last few years, the molecular mechanisms underlying the generation of complex shapes and the evolution of shape diversity are largely unknown. The emerging field of bacterial evolutionary cell biology provides a novel strategy to answer this question in a comparative phylogenetic framework. This relatively novel approach provides hypotheses and insights into cell biological mechanisms, such as morphogenesis, and their evolution that would have been difficult to obtain by studying only model organisms. We discuss the necessary steps, challenges, and impact of integrating “evolutionary thinking” into bacterial cell biology in the genomic era.

Staying in Shape: the Impact of Cell Shape on Bacterial Survival in Diverse Environments

“…Thus, much research in the bacterial morphology field focuses on defining the mechanisms by which the cell wall is synthesized and modified to produce different cell body shapes. We refer the reader to several excellent reviews on cell wall synthesis and the evolution of bacterial morphogenesis for an in-depth consideration of this topic (6)(7)(8)(9). To summarize, studies in a variety of organisms have revealed that cell shape can be derived from asymmetric positioning of new cell wall synthesis, alteration of cell wall thickness, and/or changes in the chemical composition of the cell wall polymer or its extent of cross-linking.…”

Bacterial Cell Division: Nonmodels Poised to Take the Spotlight

“…Since FtsZ is apparently the central bacterial cell division factor, the discovery of a growing number of organisms that do not encode ftsZ posed the question of how cell division occurs in these FtsZ-less bacteria (10, 43, 67, 115). One such FtsZ-less organism is an obligate intracellular pathogen, Chlamydia trachomatis .…”

Phenotypic reconstruction of the last universal common ancestor reveals a complex cell

“…This signal indicates vertical inheritance of complex microbial traits and support previous findings that trait (as opposed to gene) conservatism is widespread in bacteria and archaea 20,21 . Genetically complex traits, such as motility, shape, and the cell envelope are controlled by multiple genes [22][23][24][25] and while unlikely to be HGT free, the extent of this mechanism in the traits we study is not strong enough to blur their phylogenetic signal (see below and Methods).…”