Search

The symbiotic nitrogen fixing species Sinorhizobium meliloti represents a remarkable model system for the class Alphaproteobacteria , which includes genera such as Caulobacter , Agrobacterium and Brucella. It is capable of living free in the soil, and is also able to establish a complex symbiosis with leguminous plants, during which its cell cycle program is completely rewired presumably due, at least in part, to the action of peptides secreted by the plant. Here we will discuss how the cell cycle regulation works in S. meliloti and the kinds of molecular mechanisms that take place during the infection. We will focus on the complex regulation of the master regulator of the S. meliloti cell cycle, the response regulator CtrA, discussing its implication in symbiosis. • Sinorhizobium meliloti establishes a complex symbiosis with leguminous plants in which it differentiates in a nitrogen fixing "bacteroid" cell type. • S. meliloti cell cycle regulation is under the control of master regulators, such as the response regulator CtrA, that coordinate DNA replication, cell division and cellular motility. • CtrA and other cell cycle regulators are involved in "bacteroid" differentiation, presumably under the control of peptides produced by plants. [ABSTRACT FROM AUTHOR]