A cinetobacter strains carry two functional oligosaccharyltransferases, one devoted exclusively to type IV pilin, and the other one dedicated to O ‐glycosylation of multiple proteins

• Published in: Molecular microbiology 2015-06, Vol.96 (5), p.1023-1041
• Main Authors: Harding, Christian M., Nasr, Mohamed A., Kinsella, Rachel L., Scott, Nichollas E., Foster, Leonard J., Weber, Brent S., Fiester, Steve E., Actis, Luis A., Tracy, Erin N., Munson, Robert S., Feldman, Mario F.
• Format: Article
• Language: English
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/mmi.12986

Multiple species within the A cinetobacter genus are nosocomial opportunistic pathogens of increasing relevance worldwide. Among the virulence factors utilized by these bacteria are the type IV pili and a protein O ‐glycosylation system. Glycosylation is mediated by O ‐oligosaccharyltransferases ( O ‐OT ases), enzymes that transfer the glycan from a lipid carrier to target proteins. O ‐oligosaccharyltransferases are difficult to identify due to similarities with the WaaL ligases that catalyze the last step in lipopolysaccharide synthesis. A bioinformatics analysis revealed the presence of two genes encoding putative O ‐ OT ases or WaaL ligases in most of the strains within the genus A cinetobacter . Employing A . nosocomialis   M 2 and A . baylyi   ADP 1 as model systems, we show that these genes encode two O ‐ OT ases, one devoted uniquely to type IV pilin, and the other one responsible for glycosylation of multiple proteins. With the exception of ADP 1, the pilin‐specific OT ases in Acinetobacter resemble the TfpO/PilO O ‐O Tase from P seudomonas aeruginosa . In ADP 1 instead, the two O ‐OT ases are closely related to PglL , the general O ‐OT ase first discovered in N eisseria . However, one of them is exclusively dedicated to the glycosylation of the pilin‐like protein ComP . Our data reveal an intricate and remarkable evolutionary pathway for bacterial O ‐OT ases and provide novel tools for glycoengineering.