Open AccessOrnithine cyclodeaminase from Ti plasmid C58: DNA sequence, enzyme properties and regulation of activity by arginine
Author(s) -
SANS Notker,
SCHINDLER Ulrike,
SCHRÖDER Joachim
Publication year - 1988
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1988.tb13975.x
Subject(s) - ornithine , ti plasmid , biochemistry , agrobacterium , biology , plasmid , arginine , escherichia coli , amino acid , microbiology and biotechnology , dna , gene , transformation (genetics)
Nopaline, an abundant opine in plant cells transformed with nopaline‐type Ti plasmids, is catabolized in Agrobacterium by three Ti‐plasmid‐coded steps via arginine and ornithine to proline. The last enzyme, ornithine cyclodeaminase (OCD), converts ornithine directly into proline with release of ammonia. We describe the DNA sequence of the ocd gene from Ti plasmid C58, antiserum against an OCD fusion protein overexpressed in Escherichia coli , induction and identification of the gene product in Agrobacterium and enzymatic properties of the protein. The DNA sequence suggests a soluble protein with a stretch of some homology with ornithine carbamoyltransferases from other bacteria. OCD activity is subject to substrate inhibition, is stimulated by NAD + {presumably acting as a catalytic cofactor) and is regulated by l ‐arginine which has pronounced effects on the optima for pH and temperature and on the K m , for ornithine. The regulation of OCD activity by l ‐arginine is discussed as part of the mechanisms which integrate the pathway of Ti‐plasmid‐coded opine utilization with general metabolism in Agrobacterium.