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[12:00] InnovCrete Seminar
- 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.
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| 13:00 |
[13:00] InnovCrete Seminar
- Description:
- InnovCrete Seminar
NMR Insights on the conformational plasticity and interaction of biomolecules
Prof. George Spyroulias, Patras University, GREECE
Thursday, April 21st, 2016 @ 13:00
FORTH Amphitheatre
Host: M. Kokkinidis
The use of Modern Biomolecular NMR which is a powerful technique for the investigation of the conformational dynamics and structure-activity correlation of proteins and their complexes, provides atomic-level insights about the conformational dynamics of these biologicaly relevant molcules. To achieve this goal it is required the concerted action of molecular biology, spectroscopy and computational biology for the high-yield production of proteins in suitable forms for NMR studies (uniform labeling in 2H, 13C, 15N nuclei, and specific labeling of residues or chemical groups in 13C, 15N), the acquisition a series of NMR data and the determination of the 3D structures in solution along with the ellucidation of the relaxation properties of proteins with molecular weight ranging from 7 to >25 kDa.
Among our current research interests is the NMR-driven conformational dynamics study of disease-related enzymes and proteins, such as: (i) RNA binding proteins (~350 aminoacids) [1-2], which are key-factors in proper folding of pre-tRNA transcripts, like La autoantigen (ii) Heme-nitric oxide/oxygen binding (H-NOX) motifs (~200 amino acids), which exist as proteins or domains within larger proteins, such as soluble guanylate cyclase and function as a sensor for the gaseous signaling agent nitric oxide (NO) that regulates the catalytic site contained within the C-terminal end of the enzyme [3], (iii) macro domains (~170 aminoacids), which are evolutionarily conserved in eukaryotic organisms, bacteria and archaea and they are also found in nonstructural proteins (nsPs) of several positive-strand RNA viruses, including hepatitis E virus, rubella virus and coronaviruses, as well as alphaviruses [4-5], (iv) various E3 ubiquitin ligases involved in ubiquitination pathway, like ARKADIA tumor suppressor [6-7], (v) extracellular domains of ligand-gated ion channels of the cys-loop family (nAChR is the prototype) that involved in various neurodegenerative disorders [8], and others.
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April 2016
