Microbial Genetics Laboratory・Niki Group
Comparative Genomics Laboratory・Fujiyama Group
Genome Biology Laboratory・Kohara Group

Wild-type E. coli are rod shape (Figure A, left). To make rod shaped cells, it is necessary that many proteins form complexes and function properly. E. coli cells are surrounded by rigid peptidoglycan (PG) layer and have to synthesize PG correctly. So far, we have identified RodZ required for determination of cell shape.

RodZ-deficient mutant is round shape (Figure A, middle) and grows slower than wild-type E. coli cell. To reveal function of RodZ protein, we isolated suppressor mutants that restore cell growth and shape of the rodZ mutant. To map the mutation sites in the suppressor mutants, we sequenced whole genome of twenty-nine mutants by a next-generation sequencer Solexa. This is the first report that mutation sites in ~30 mutants are determined by whole genome sequencing.

Most of the mutations were found in mreB, mrdA, or mrdB genes. It has been hypothesized that MreB, PBP2 encoded by mrdA gene, and RodA encoded by mrdB gene function with RodZ. Especially, twenty of twenty-nine mutants had a mutation in mreB gene. In addition, these mutations were clustered in domain 1A, one of the subdomain of MreB protein. These mutations change properties of MreB protein so that E. coli can form rod shape without RodZ protein. We also found that mutants of PBP2 and RodA change properties of MreB. Thus, we concluded that RodZ regulates function of MreB to form rod shape of E. coli.

This work was done by a collaboration of Niki lab, Fujiyama lab, and Kohara lab.

(A) Wild-type E. coli is rod (left). RodZ-deficient E. coli cell is round (middle). Suppressor mutants are rod (right).
(B) Mutation sites shown by purple are clustered in domain 1A and it is a surface between MreB filaments. These mutations change properties of MreB filaments.