The active repertoire of <i>Escherichia coli</i> peptidoglycan amidases varies with physiochemical environment

Mueller, Elizabeth A.; Iken, A. G.; Öztürk, Mehmet Ali; Winkle, Matthias; Schmitz, Mirko; Vollmer, Waldemar; Ventura, Barbara Di; Levin, Petra Anne

doi:10.1111/mmi.14711

Cited by 30 publications

(41 citation statements)

References 86 publications

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“…We next assessed whether the lysis phenotype of the araB p lptC Δ actS mutant can be rescued by the deletion of amiC and found that lack of AmiC does not protect from lysis under nonpermissive conditions (Figure S6 a). This result is consistent with data reported in the accompanying manuscript (Mueller et al., 2021 ) where AmiA is shown to be sufficient for normal cell separation under neutral and acidic conditions. Finally, we show that deletion of nlpD does not suppress the lysis phenotype of lptC ‐depleted actS ‐deleted cells (Figure S6 b), further supporting the notion that there is a specific functional connection between LdtF and ActS.…”

Section: Resultssupporting

confidence: 93%

“…Here we showed that AmiC is not only activated by the previously identified NlpD but is also by ActS. In the accompanying paper, the Levin group shows that cells growing at acidic conditions rely mostly on AmiB and its activation by NlpD, EnvC, and ActS for cell separation (Mueller et al, 2021). Hence, the simplistic view of each amidase having one activator has to be revised and more work is needed to decipher the mechanisms of PG cleavage during cell division under different growth conditions.…”

Section: Discussionmentioning

confidence: 83%

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ActS activates peptidoglycan amidases during outer membrane stress in Escherichia coli

Serrano

Winkle

Martorana

et al. 2021

Molecular Microbiology

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Section: Resultssupporting

confidence: 93%

Section: Discussionmentioning

confidence: 83%

ActS activates peptidoglycan amidases during outer membrane stress in Escherichia coli

Serrano

Winkle

Martorana

et al. 2021

Molecular Microbiology

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“…Regarding the other activities, the multiple deficiency in S. Typhimurium of candidates like the amidases AmiA/AmiB/AmiC (cleavage of NAM-L-Ala) or the D,D-carboxypeptidases PBP4/PBP5/PBP6 /PBP6b/PBP7 (cleavage of D-Ala-D-Ala in stem peptide), results in gross morphological changes that prevent their usage in infection assays of cultured mammalian cells. Our observations are consistent with the morphological alterations reported in E. coli mutants lacking some of the AmiA/AmiB/AmiC amidases [57,59] or multiple D,D-carboxypeptidases [51]. Therefore, before isolating PG material from bacteria recovered from intracellular infections, we focused on those S. Typhimurium mutants exhibiting normal rod shape and capacity to invade cultured fibroblasts: i) ΔycbB ΔynhG; ii) ΔamiA ΔamiC; iii) ΔamiA ΔamiB; and, iv) ΔdacC ΔdacD.…”

Section: Plos Pathogenssupporting

confidence: 86%

Peptidoglycan editing in non-proliferating intracellular Salmonella as source of interference with immune signaling

et al. 2022

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Salmonella enterica causes intracellular infections that can be limited to the intestine or spread to deeper tissues. In most cases, intracellular bacteria show moderate growth. How these bacteria face host defenses that recognize peptidoglycan, is poorly understood. Here, we report a high-resolution structural analysis of the minute amounts of peptidoglycan purified from S. enterica serovar Typhimurium (S. Typhimurium) infecting fibroblasts, a cell type in which this pathogen undergoes moderate growth and persists for days intracellularly. The peptidoglycan of these non-proliferating bacteria contains atypical crosslinked muropeptides with stem peptides trimmed at the L-alanine-D-glutamic acid-(γ) or D-glutamic acid-(γ)-meso-diaminopimelic acid motifs, both sensed by intracellular immune receptors. This peptidoglycan has a reduced glycan chain average length and ~30% increase in the L,D-crosslink, a type of bridge shared by all the atypical crosslinked muropeptides identified. The L,D-transpeptidases LdtD (YcbB) and LdtE (YnhG) are responsible for the formation of these L,D-bridges in the peptidoglycan of intracellular bacteria. We also identified in a fraction of muropeptides an unprecedented modification in the peptidoglycan of intracellular S. Typhimurium consisting of the amino alcohol alaninol replacing the terminal (fourth) D-alanine. Alaninol was still detectable in the peptidoglycan of a double mutant lacking LdtD and LdtE, thereby ruling out the contribution of these enzymes to this chemical modification. Remarkably, all multiple mutants tested lacking candidate enzymes that either trim stem peptides or form the L,D-bridges retain the capacity to modify the terminal D-alanine to alaninol and all attenuate NF-κB nuclear translocation. These data inferred a potential role of alaninol-containing muropeptides in attenuating pro-inflammatory signaling, which was confirmed with a synthetic tetrapeptide bearing such amino alcohol. We suggest that the modification of D-alanine to alaninol in the peptidoglycan of non-proliferating intracellular S. Typhimurium is an editing process exploited by this pathogen to evade immune recognition inside host cells.

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“…Presumably an ATPase dependent conformational change in FtsEX induces a conformational change in EnvC, which is then able to relieve an autoinhibitory alpha-helix from the active site of AmiA and AmiB, activating them [44]. The third amidase AmiC is activated by the OM-anchored lipoprotein NlpD [24] and all three amidases AmiA-C are activated under certain stress conditions by the recently identified ActS [46,47]. The recruitment of the other cell division proteins occurs with a time delay of about 20% of the cell division cycle, depending on the growth condition [48][49][50].…”

Section: Introductionmentioning

confidence: 99%

Midcell localization of PBP4 ofEscherichia colimodulates the timing of divisome assembly

Verheul

Lodge

Yau

et al. 2020

Preprint

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Insertion of new material into the Escherichia coli peptidoglycan (PG) sacculus between the cytoplasmic membrane and the outer membrane requires a well-organized balance between synthetic and hydrolytic activities to maintain cell shape and avoid lysis. The hydrolytic enzymes outnumber the enzymes that insert new PG by far and very little is known about their specific function. Here we show that the DD-carboxy/endopeptidase PBP4 localizes in a PBP1A/LpoA and FtsEX dependent fashion at midcell during septal PG synthesis. Midcell localization of PBP4 requires its non-catalytic domain 3 of unknown function, but not the activity of PBP4 or FtsE. Domain 3 is also needed for the interaction of PBP4 with NlpI, but not for its interactions with PBP1A or LpoA. Microscale thermophoresis with isolated proteins shows that domain 3 is needed for the interaction with NlpI, but not PBP1A or LpoA. In vivo crosslinking experiments confirm the interaction of PBP4 with PBP1A and LpoA. We propose that PBP4 functions together with the amidases AmiA and B to create denuded glycan strands to attract the initiator of septal PG synthesis, FtsN. Consistent with this model, we found that the arrival of FtsN and other cell division proteins at midcell was significantly delayed in cells lacking PBP4.

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The active repertoire of Escherichia coli peptidoglycan amidases varies with physiochemical environment

Cited by 30 publications

References 86 publications

ActS activates peptidoglycan amidases during outer membrane stress in Escherichia coli

ActS activates peptidoglycan amidases during outer membrane stress in Escherichia coli

Peptidoglycan editing in non-proliferating intracellular Salmonella as source of interference with immune signaling

Midcell localization of PBP4 ofEscherichia colimodulates the timing of divisome assembly

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