GTPase Activity of Mycobacterial FtsZ Is Impaired Due to Its Transphosphorylation by the Eukaryotic-type Ser/Thr Kinase, PknA

Meghna Thakur,Pradip K Chakraborti

doi:10.1074/jbc.m607216200

Meghna Thakur, Pradip K Chakraborti

Open Access

https://doi.org/10.1074/jbc.m607216200

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Abstract

FtsZ, a homolog of eukaryotic tubulin, is involved in the process of cell division, particularly in septum formation in bacteria. The primary amino acid sequences of this protein are fairly conserved in prokaryotes. We observed that a eukaryotic-type Ser/Thr protein kinase, PknA from Mycobacterium tuberculosis, when expressed in Escherichia coli exhibited cell elongation due to a defect in septum formation. We found that FtsZ either from Escherichia coli (eFtsZ) or from M. tuberculosis (mFtsZ) was phosphorylated on co-expression with PknA. Consistent with these observations, solid phase binding and in vitro kinase assays revealed the ability of PknA to interact with mFtsZ protein and also to phosphorylate it. We, therefore, ascertained mFtsZ as a substrate of PknA. Furthermore, the phosphorylated mFtsZ exhibited impairment in its GTP hydrolysis and polymerization abilities. Thus, our results highlighted the ability of PknA to phosphorylate as well as to regulate the functionality of FtsZ, the protein central to cell division throughout the bacterial lineage.

Highlights

The ring-like structure is primarily composed of FtsZ protein, which is the key molecule responsible for initiating the earliest event in the process of septation
PknA Expression in E. coli Exhibited Elongated Cells with Segregated Nucleoids—We previously reported that constitutive expression of the pknA open reading frame of M. tuberculosis in E. coli resulted in a remarkable elongation of cells [15]
The elongated morphology might be the result of an imperfection in septum formation, which is the later stage in the process of cell division

Summary

Introduction

The ring-like structure is primarily composed of FtsZ protein, which is the key molecule responsible for initiating the earliest event in the process of septation. In vitro assays with PknA showed its ability to phosphorylate M. tuberculosis FtsZ (mFtsZ)3 protein. In concordance with this observation, our results indicated that mFtsZ was phosphorylated on co-expression with PknA in E. coli cells.

Results

Conclusion