IDENTIFICATION OF NOVEL COMPONENT OF RIBOFLAVIN BIOSYNTHETIC PATHWAY IN INVASIVE BACTERIA

Abstract

Riboflavin biosynthetic pathway of Sinorhizobium meliloti1021 has a potential alternative enzyme ArfB, essential in riboflavin production for intracellular use. ArfB forms complexes with riboflavin biosynthetic enzymes in S. meliloti1021. The objective of this study was to identify the novel enzymes involved in the riboflavin biosynthesis of riboflavin prototrophic revertant strain Rm1021∆arfBxOa arfB and analyze the free-living phenotypes and the symbiotic phenotypes. Whole genome sequencing was conducted and several SNPs and indels were identified in the genome of revertants, specifically in genes phnM, SMc00185, and argG. The revertant strains could not form effective symbiosis and exhibited lower growth-rate and flavin secretion compare to the control. Occasionally some revertants exhibited effective symbiosis. Secondary revertants were isolated and sequenced for identification of variations. Genetic modifications were observed on the SMb21442 and Oa arfB genes. Characterization of identified genes in future experiments will provide comprehensive understanding of the functions in riboflavin metabolism of α-proteobacteria.