Genetics of serine pathway enzymes in Methylobacterium extorquens AM1: phosphoenolpyruvate carboxylase and malyl coenzyme A lyase.
Methylobacterium extorquens AM1 is a facultative methylotrophic bacterium that uses the serine pathway for formaldehyde incorporation as its assimilation pathway during growth on one-carbon compounds. A DNA region from M. extorquens AM1 previously shown to contain genes for the serine pathway enzymes malyl coenzyme A (CoA) lyase and hydroxypyruvate reductase has been characterized in more detail. Insertion mutagenesis revealed an additional region required for growth on one-carbon compounds, and all of the insertion mutants in this region lacked activity for another serine pathway enzyme, the acetyl-CoA-independent phosphoenolpyruvate (PEP) carboxylase. Expression analysis with Escherichia coli of DNA fragments that included the malyl-CoA lyase and PEP carboxylase regions identified five polypeptides, all transcribed in the same direction. Three of these polypeptides were expressed from the region necessary for the acetyl-CoA-independent PEP carboxylase, one was expressed from the region containing the malyl-CoA lyase gene, and the fifth was expressed from a region immediately downstream from the gene encoding hydroxypyruvate reductase. All six genes are transcribed in the same direction, but the transposon insertion data suggest that they are not all cotranscribed.
Keck Laboratories, California Institute of Technology, Pasadena 91125.
P J
PJ
Arps
G F
GF
Fulton
E C
EC
Minnich
M E
ME
Lidstrom
D001426:Bacterial Proteins / Q000235:genetics; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D006088:Gram-Negative Aerobic Bacteria / Q000201:enzymology / Q000235:genetics*; D008970:Molecular Weight; D016254:Mutagenesis, Insertional; D007652:Oxo-Acid-Lyases / Q000378:metabolism*; D010730:Phosphoenolpyruvate Carboxylase / Q000235:genetics*; D015183:Restriction Mapping; D012694:Serine / Q000378:metabolism*
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012694:Serine; D010730:Phosphoenolpyruvate Carboxylase; D007652:Oxo-Acid-Lyases; C021536:malyl-CoA lyase