Aerobic degradation of choline by Proteus mirabilis: enzymatic requirements and pathway.
Cleavage of choline to trimethylamine and acetaldehyde by extracts of Proteus mirabilis requires both particulate and soluble protein fractions, K+, and a bound divalent metal cation. The reaction shows a long lag period, abolished only by preincubation of the particulate fraction in the complete reaction system. The two-carbon fragment produced is acetaldehyde; choline cleavage appears to be tightly coupled to dismutation of the acetaldehyde to ethanol and acetate, as indicated by stimulation by NAD+, ADP, and Fe2+ and inhibition by reagents reacting with acetaldehyde. The system is thus similar to that previously described in anaerobes (Desulfovibrio, Clostridium). Attempts to demonstrate a cobamide coenzyme requirement (as in the similar ethanolamine ammonia-lyase reaction) were unsuccessful; the reaction was carried out by fractions devoid of vitamin B12 activity (not supporting growth of Lactobacillus leichmannii) and insensitive to light.
D000079:Acetaldehyde / Q000032:analysis; D000332:Aerobiosis; D002474:Cell-Free System; D002794:Choline / Q000031:analogs & derivatives / Q000378:metabolism*; D007700:Kinetics; D008744:Methylamines / Q000032:analysis; D011513:Proteus mirabilis / Q000201:enzymology*
D008744:Methylamines; D000079:Acetaldehyde; C023336:trimethylamine; D002794:Choline