Eldar Yagmurov (deceased), Konstantin Gilep, Svetlana Dubiley and Konstantin Severinov from Skoltech have published a paper “S51 Family Peptidases Provide Resistance to Peptidyl-Nucleotide Antibiotic McC” in mBio journal. The researchers describe a new strategy through the action of S51 family peptidases, which they name MccG. The ribosomally synthesized peptide parts of microcin C and related antibiotics are responsible for their facilitated transport into susceptible cells. Once inside the cell, the peptide part is degraded, releasing the toxic payload, an isoaspartyl-nucleotide that inhibits aspartyl-tRNA synthetase, an enzyme essential for protein synthesis. Bacteria that produce microcin C-like compounds have evolved multiple ways to avoid self-intoxication. The scientists show that MccG cleaves the toxic isoaspartyl-nucleotide, rendering it inactive. Full text of the paper is available here.