This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hong, S B Articles by Farrand, S K Search for Related Content PubMed PubMed Citation Articles by Hong, S B Articles by Farrand, S K

 Previous Article  |  Next Article 

J Bacteriol. 1994 June; 176(12): 3576-3583

research-article

Functional role of the Ti plasmid-encoded catabolic mannopine cyclase in mannityl opine catabolism by Agrobacterium spp.

Department of Plant Pathology, University of Illinois at Urbana-Champaign 61801.

ABSTRACT

Catabolic mannopine (MOP) cyclase encoded by Ti or Ri plasmids lactonizes MOP to agropine (AGR). The gene of the octopine-type Ti plasmid pTi15955 encoding the catabolic MOP cyclase enzyme previously was localized to a 1.6-kb segment within a cosmid clone, pYDH208. A subclone containing only this region complemented the AGR catabolism-negative phenotype conferred by a derivative of the octopine-type plasmid pTiB6S3 containing a Tn7 insertion in the region encoding the MOP cyclase enzyme. Uptake assays of strains harboring pRiA4 or pArA4a, along with complementation analyses, indicate that MOP cyclase is not sufficient for catabolism of AGR but that the strains must also express an AGR transport system. To determine the requirement for MOP cyclase in opine catabolism unequivocally, a site-specific, nonpolar deletion mutation abolishing only MOP cyclase activity was introduced into pYDH208, a cosmid clone that confers utilization of MOP, AGR, and mannopinic acid (MOA). Strains harboring this MOP cyclase-negative mutant clone, pYDPH208, did not utilize AGR but continued to utilize MOP. Growth on AGR was restored in this strain upon introduction of clones encoding the pTi15955-derived catabolic or anabolic MOP cyclase genes. The induction pattern of MOA catabolism shown by strain NT1 harboring the MOP cyclase-deficient pYDPH208 suggests that AGR is converted into MOP by MOP cyclase and that MOP, but not AGR, induces catabolism of MOA. Genetic and biochemical analyses of MOP and AGR metabolism suggest that only the conversion of AGR to MOP is directly involved in catabolism of AGR, even though the reaction catalyzed by MOP cyclase predominantly lies in the lactonization of MOP to AGR.

This article has been cited by other articles:

• Baek, C.-H., Farrand, S. K., Lee, K.-E., Park, D.-K., Lee, J. K., Kim, K.-S. (2003). Convergent Evolution of Amadori Opine Catabolic Systems in Plasmids of Agrobacterium tumefaciens. J. Bacteriol. 185: 513-524 [Abstract] [Full Text]