Novel Role of Phosphorylation-Dependent Interaction between FtsZ and FipA in Mycobacterial Cell Division

The bacterial divisome is a multiprotein complex. Specific protein-protein interactions specify whether cell division occurs optimally, or whether division is arrested. Little is known about these protein-protein interactions and their regulation in mycobacteria. We have investigated the interrelationship between the products of the Mycobacterium tuberculosis gene cluster Rv0014c-Rv0019c, namely PknA (encoded by Rv0014c) and FtsZ-interacting protein A, FipA (encoded by Rv0019c) and the products of the division cell wall (dcw) cluster, namely FtsZ and FtsQ. M. smegmatis strains depleted in components of the two gene clusters have been complemented with orthologs of the respective genes of M. tuberculosis. Here we identify FipA as an interacting partner of FtsZ and FtsQ and establish that PknA-dependent phosphorylation of FipA on T77 and FtsZ on T343 is required for cell division under oxidative stress. A fipA knockout strain of M. smegmatis is less capable of withstanding oxidative stress than the wild type and showed elongation of cells due to a defect in septum formation. Localization of FtsQ, FtsZ and FipA at mid-cell was also compromised. Growth and survival defects under oxidative stress could be functionally complemented by fipA of M. tuberculosis but not its T77A mutant. Merodiploid strains of M. smegmatis expressing the FtsZ(T343A) showed inhibition of FtsZ-FipA interaction and Z ring formation under oxidative stress. Knockdown of FipA led to elongation of M. tuberculosis cells grown in macrophages and reduced intramacrophage growth. These data reveal a novel role of phosphorylation-dependent protein-protein interactions involving FipA, in the sustenance of mycobacterial cell division under oxidative stress

Design, instrumentation, and operation of a standard downdraft, laboratory-scale gasification testbed utilising novel seed-propagated hybrid Miscanthus pellets

Biomass gasification remains an attractive option to impact climate chaos; however, the technology presents challenges in tolerance to feedstock variability and tar production, which can limit the overall process efficiency, gasifier performance, durability and downstream syngas utilisation. The primary objectives of this study were to compare two gasifier design approaches using different reaction kinetics, based on multiple or singular oxidation and gasification reactions, and build and test a novel, flexible, laboratory-scale downdraft gasifier to convert pellets from UK hybrid Miscanthus into syngas, whilst deploying inexpensive instrumentation methods. The experimental gasification parameters studied were carbon conversion efficiency, gas yield, cold gas efficiency and gas heating values. The performance study shows that the system achieved good average temperature (842–866 °C) in the reduction zones for equivalence ratios between 0.25 and 0.35. The optimum values for carbon conversion efficiency, cold gas efficiency, heating values (HHV) of product gas and gas yield were 74%, 32%, 4.17 MJ/m3 and 1.32 m3/kg(biomass), respectively. The reported performance parameters for the new seed-propagated hybrid Miscanthus in the present study were comparable to those from conventional Miscanthus pellet gasification in downdraft gasifiers but these new hybrid varieties offer advantages in productivity over broader climatic regions compared to conventional varieties