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| Description: | InnovCrete Seminar Regulation of bacterial cell wall growth Prof. Waldemar Vollmer, Newcastle University, UK Thursday, April 21st, 2016 @ 12:00 FORTH Amphitheatre Host: M. Kokkinidis The bacterial cell envelope has a complex structure and must be enlarged when the cell grows and divides. Gram-negative bacteria have in their periplasm a mainly single-layered peptidoglycan sacculus that protects the cell from lysis due to the turgor and that is required to maintain cell shape. During growth and cell division the sacculus is enlarged by the coordinated activities of peptidoglycan synthases (penicillin-binding proteins, PBPs) and hydrolases, which presumably form dynamic multi-enzyme complexes. The molecular mechanisms of peptidoglycan growth and its regulation are poorly understood. Cytoskeletal proteins and associated cell morphogenesis proteins control peptidoglycan synthesis from inside the cell, within large cell envelope assemblies called elongasome and divisome. Recent work showed that peptidoglycan growth is also regulated from outside the sacculus in Escherichia coli and likely other Gram-negative bacteria. The outer membrane lipoproteins LpoA and LpoB are required for the functioning of the main peptidoglycan synthases, PBP1A and PBP1B, respectively. Lpo proteins interact with their cognate PBP and activate the transpeptidase function in vitro. The Lpo-interaction occurs with small, non-catalytic domains that have co-evolved with the outer-membrane activators. Presumably, Lpo proteins regulate peptidoglycan synthesis form outside the sacculus to maintain a homogenous peptidoglycan surface density and thickness, and to fine-tune peptidoglycan growth rate. PBP1A-LpoA are mainly active during cell elongation, and PBP1B-LpoB are members of the divisome and provide the main peptidoglycan synthesis activity during cell division. I will present recent structural data showing how LpoA and LpoB are able to span the periplasm to interact with their cognate PBP. Recent data also show that PBP1B-LpoB are modulated by CpoB, a protein that is required to coordinate peptidoglycan synthesis with outer membrane constriction during cell division. |
| Location: | FORTH Amphitheatre |
| Status: | Waiting for approval |
| Date: | Thursday, April 21, 2016 |
| Time: | 12:00 EEST |
| Priority: | 5-Medium |
| Access: | Public |
| Created by: | Lila Kalogeraki |
| Updated: | Thursday, April 21, 2016 08:51 GMT |