KerA

kerA is a gene symbol used in multiple organisms to denote a keratinase gene, typically encoding an enzyme that degrades keratin, a tough structural protein found in feathers, hair, nails, and related materials. In many Bacillus species, kerA commonly refers to a secreted protease that acts on keratin and other protein substrates. The kerA-encoded enzyme is often a serine protease of the subtilisin-like family, produced as a preproenzyme with an N-terminal signal sequence and a propeptide, and is activated by proteolytic processing after secretion.

Biochemical properties of kerA-encoded keratinases vary by organism but many exhibit activity under alkaline conditions and require metal ions such as calcium for stability. They are capable of hydrolyzing insoluble keratin and can show broad substrate specificity, including other protein substrates under suitable conditions. Regulation of kerA expression commonly responds to the presence of keratin or keratin-containing materials, enabling the organism to exploit keratin as a nutrient source. Environmental conditions such as pH, temperature, and salinity influence enzyme activity and stability.

Applications and industrial relevance: kerA-derived keratinases are studied for valorizing keratin-rich waste, such as poultry feathers, by breaking down keratin into peptides and amino acids. This has potential applications in producing animal feed additives, enabling bioconversion of waste streams, and contributing to leather, textile, or cosmetic processing workflows where keratin degradation is desirable.

Genomic context: because kerA is a common gene symbol, its precise location and neighboring genes differ among species. Readers should consult organism-specific genome annotations to determine the exact gene context. See also keratinase and subtilisin-like proteases for related context.