A region of the Agrobacterium tumefaciens chromosome containing genes required for virulence and attachment to host cells

A 29 kb region of the circular chromosome of Agrobacterium tumefaciens cont aining genes required for bacterial attachment to host cells and virulence has been sequenced. Transposon mutants in many of the genes have been obtai ned. The mutants can be divided into two groups: those which can be complem ented by conditioned medium and those whose phenotype is unaffected by cond itioned medium. The first group includes mutants in genes with homology to ABC transporters, one possible transcriptional regulator, and some closely linked genes immediately downstream. The second group includes mutants in t wo possible transcriptional regulators, one ATPase, and a number of biosynt hetic genes including a transacetylase required for the formation of an ace tylated capsular polysaccharide. There are also several genes with no homol ogy to genes of identified function. The presence of such a large number of genes required for attachment to host cells suggests that the ability of A . tumefaciens to bind to plant cells may play an important role in the life of these bacteria. (C) 2000 Elsevier Science B.V. All rights reserved.