AmoC

AmoC is a gene encoding one of the subunits of the ammonia monooxygenase (AMO) enzyme complex found in ammonia-oxidizing bacteria (AOB) and, in some instances, ammonia-oxidizing archaea (AOA). In many bacteria, amoA, amoB, and amoC are encoded together in an operon and expressed to form the membrane-bound AMO that catalyzes the oxidation of ammonia to hydroxylamine, the first step of nitrification.

Function and structure: AmoA is generally considered the catalytic subunit of AMO, while AmoB and AmoC are believed to contribute to proper assembly, stability, and electron transfer within the complex. The precise role of AmoC remains under investigation, but it is predicted to be an integral membrane protein with transmembrane regions that interfaces with the other subunits to support enzyme function.

Taxonomy and distribution: amoCAB genes have been identified in several genera of AOB, such as Nitrosomonas and Nitrosococcus, and are present in some AOAs, though sequence diversity exists across lineages. Ecological relevance: AMO genes are widely used as markers for nitrification potential in environmental microbiology; AmoC sequences complement information from amoA studies and aid in phylogenetic analyses of AMO-containing organisms.

Discovery and history: The AMO enzyme and its subunits were characterized through studies of bacterial nitrification in the late 20th century, with AmoA, AmoB, and AmoC identified as components of the ammonia-oxidizing machinery. Further research continues to clarify the specific contributions of AmoC to enzyme assembly and activity.