biostudies-literatureDai YUmea UniversityThe laboratory of Molecular Infection Medicine SwedenNIAID NIH HHSKnut och Alice Wallenbergs StiftelseHHS | NIH | National Institute of Allergy and Infectious DiseasesKempestiftelsernaSwedish Research CouncilNortheastern Universitye0278621https://www.ebi.ac.uk/biostudies/studies/S-EPMC8649774biostudies-literatureUnknown12(6)The hospital-acquired pathogen Acinetobacter baumannii possesses a complex cell envelope that is key to its multidrug resistance and virulence. The bacterium, however, lacks many canonical enzymes that build the envelope in model organisms. Instead, A. baumannii contains a number of poorly annotated proteins that may allow alternative mechanisms of envelope biogenesis. We demonstrated previously that one of these unusual proteins, ElsL, is required for maintaining a characteristic short rod shape and for withstanding antibiotics that attack the septal cell wall. Curiously, ElsL is composed of a leaderless YkuD-family domain usually found in secreted, cell wall-modifying l,d-transpeptidases (LDTs). Here, we show that, rather than being an LDT, ElsL is actually a new class of cytoplasmic l,dmBioA New Class of Cell Wall-Recycling l,d-Carboxypeptidase Determines β-Lactam Susceptibility and Morphogenesis in Acinetobacter baumannii.PMC8649774R01AI162996R01 AI162996Geisinger ETang AYCava FDai YPinedo VfalseA New Class of Cell Wall-Recycling l,d-Carboxypeptidase Determines β-Lactam Susceptibility and Morphogenesis in Acinetobacter baumannii.The hospital-acquired pathogen Acinetobacter baumannii possesses a complex cell envelope that is key to its multidrug resistance and virulence. The bacterium, however, lacks many canonical enzymes that build the envelope in model organisms. Instead, A. baumannii contains a number of poorly annotated proteins that may allow alternative mechanisms of envelope biogenesis. We demonstrated previously that one of these unusual proteins, ElsL, is required for maintaining a characteristic short rod shape and for withstanding antibiotics that attack the septal cell wall. Curiously, ElsL is composed of a leaderless YkuD-family domain usually found in secreted, cell wall-modifying l,d-transpeptidases (LDTs). Here, we show that, rather than being an LDT, ElsL is actually a new class of cytoplasmic l,d2021-01-01T00:00:00Z2021 Dec2026-06-12T10:27:52.432Z2022-02-11T15:39:59.562ZS-EPMC86497743487235010.1128/mBio.02786-21