Sequence and structural analysis of FtsZ homologs and comparison of bacterial FTsZ with eukaryotic tubulins

Radha Mahendran

doi:10.17485/ijst/2011/v4i2.9

Abstract

FtsZ, a bacterial cell division protein is a homolog of eukaryotic tubulins. It was postulated that FtsZ of different bacterial species might have specific signature sequences, based on which various FtsZ protein sequences were classified, mined and analyzed. Multiple sequence alignment of the sequences resulted in the highly specific signatures at the C-terminal end of gram-negative bacterial FtsZ. Interestingly, a few organisms belonging to the phylum Bacteroidetes were found to contain 600-650 amino acid-FtsZ sequences having an extra long spacer residues of about 300-350 amino acids. Sequentially, the spacer showed the presence of coils throughout using secondary structure prediction methods. Structurally over a span of 133 residues, a match was found in T7 DNA ligase, suggesting the presence of viral origin of the extra residues. Eukaryotic α-tubulins were also mined and aligned giving rise to high percentage identity even among highly diverged species such as the zebra fish and humans. This suggests the reason behind the high divergence seen between the eukaryotes and the prokaryotes sequentially, though structurally they share 98% similarity. The main focus of the present work was to understand evolution of the bacterial and eukaryotic cytoskeleton proteins.

Highlights

FtsZ, a major cytoskeleton protein present in bacteria, is a polymer forming GTPase, which drives bacterial cell division
X and were checked for the signature sequences. Another set of sequences belonging to the class Gammaproteobacteria, phylum Firmicutes, Bacteroidetes and Euryarchaeota were collected which lacked the conserved C-terminal end (Vaughan et al, 2004)
Gram-positive organisms obtained by blasting against the FtsZ sequence of Bacillus subtilis strain

Summary

Introduction

FtsZ, a major cytoskeleton protein present in bacteria, is a polymer forming GTPase, which drives bacterial cell division. FtsZ contains 4 main domains, as determined by the crystal structure of FtsZ from Archaea Methanococcus jannaschii (Lowe & Amos, 1998). They comprise of variable Nterminus, the highly conserved core region, a variable spacer region and the C-terminus region. The core region is a stretch of approximately 300 amino acids which contains all of the residues required for GTP binding and hydrolysis This particular region is highly conserved in all the tubulins and in FtsZ. The C-terminal is not required for assembly, but is essential for the interactions with other membrane proteins FtsA, ZipA, SepF and EzrA (Singh et al, 2007, 2008). Some of these proteins help in the polymerization and stability the Z rings

Objectives

Methods

Results