Abstract
Peptidoglycan (PG) is an essential constituent of the bacterial cell wall. During cell division, the machinery responsible for PG synthesis localizes mid-cell, at the septum, under the control of a multiprotein complex called the divisome. In Escherichia coli , septal PG synthesis and cell constriction rely on the accumulation of FtsN at the division site. Interestingly, a short sequence of FtsN (L75 to Q93, known as E FtsN) was shown to be essential and sufficient for its functioning in vivo , but what exactly this sequence is doing remained unknown. Here, we show that E FtsN binds specifically to the major PG synthase PBP1b and is sufficient to stimulate its biosynthetic glycosyltransferase (GTase) activity. We also report the crystal structure of PBP1b in complex with E FtsN, which demonstrates E FtsN binds at the junction between the GTase and UB2H domains of PBP1b. Interestingly, mutations to two residues (R141A/R397A) within the E FtsN binding pocket reduced the activation of PBP1b by FtsN but not by the lipoprotein LpoB. This mutant was unable to rescue Δ pon B- pon Ats strain, that lack PBP1b and has a thermosensitive PBP1a, at nonpermissive temperature and induced a mild cell chaining phenotype and cell lysis. Altogether, the results show that E FtsN interacts with PBP1b and that this interaction plays a role in the activation of its GTase activity by FtsN, which may contribute to the overall septal PG synthesis and regulation during cell division.
Original language | English |
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Pages (from-to) | 18256-18265 |
Journal | Journal of Biological Chemistry |
Volume | 295 |
Issue number | 52 |
DOIs | |
Publication status | Published - 25 Dec 2020 |
Keywords
- eptidoglycan
- divisome
- penicillin-binding protein 1b (PBP1b)
- FtsN
- lipid II
- bacteria
- cell division
- cellular regulation
- cell surface enzyme
- cell wall