Organization of the genes involved in the ribulose monophosphate pathway in an obligate methylotrophic bacterium, Methylomonas aminofaciens 77a

The 4.4-kb PstI fragment harboring the gene encoding 3-hexulose-6-phosphate synthase, rmpA, which was previously cloned from the chromosome of an obli gate methylotroph, Methylomonas aminofaciens 77a, was investigated in detai l. In addition to the rmpA gene, the fragment contained three open reading frames encoding transaldolase (rmpD), IS10-R (rmpI), and 6-phospho-3-hexulo isomerase (PHI) (rmpB). The rmpB gene product was overproduced in Escherich ia coli cells, purified to homogeneity, and then enzymatically identified a s PHI. The gene organization of the ribulose monophosphate pathway enzymes together with a transposon, IS10-R, is discussed from both evolutionary and regulatory aspects. (C) 1999 Published by Elsevier Science B.V. All rights reserved.