CHARACTERIZATION OF MOEB - PART OF THE MOLYBDENUM COFACTOR BIOSYNTHESIS GENE-CLUSTER IN STAPHYLOCOCCUS-CARNOSUS

Transposon mutagenesis of Staphylococcus carnosus led Ic the identific ation of a fee cluster comprising nine genes that are important For mo lybdenum cofactor biosynthesis. Two nitrate-reductase-negative Tn917-i nsertion mutants were defective in MoeB. III cell-free extracts of an moeB mutant, the molybdenum-cofactor-deficient nitrate reductase could be reconstituted with a low-molecular-mass component (most likely fre e molybdenum cofactor) from an S. carnosus mutant that is defective in the nitrate reductase structural genes. The expression of moeB was st udied in response to oxygen and nitrate. Primer-extension studies indi cated that anaerobiosis and nitrate each enhance transcription of moeB . (C) 1998 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.