Characterization of the Mycoplasma hominis ftsZ gene and its sequence variability in mycoplasma clinical isolates K.T. Momynaliev, a O.V. Smirnova, a V.N. Lazyrev, a T.A. Akopian, a V.V. Chelysheva, a J.A. Ayala, b, * A.N. Simankova, c S.N. Borchsenius, c and V.M. Govorun a a Institute of Physico-Chemical Medicine, Malaya Pirogovskaya Str. 1A, Moscow 119992, Russia b Centro de Biologia Molecular ‘‘Severo Ochoa,’’ Consejo Superior de Investigaciones Cientificas, Cantoblanco, Madrid 28049, Spain c Institute of Cytology, Russian Academy of Sciences, Tikhoretsky Avenue 4, St. Petersburg 194064, Russia Received 8 March 2002 Abstract We cloned and sequenced Mycoplasma hominis chromosomal fragment containing ftsZ gene. The wild-type expression of the gene was shown at RNA level by reverse transcription followed by PCR amplification. We revealed that M. hominis FtsZ had a comparatively low similarity to proteins of Mycoplasma genitalium and Mycoplasma pneumoniae.Afterfull ftsZ gene sequencing for 14 clinical isolates of M. hominis, single-nucleotide substitutions were found in 21 positions, 6 of them being common for almost all isolates. This ftsZ gene polymorphism may be used for subtyping of M. hominis in clinical samples. Expression of the M. hominis ftsZ gene in different Escherichia coli strains was also demonstrated, and M. hominis FtsZ protein was purified from E. coli cells transformed with recombinant expression plasmid. Complementation between the M. hominis FtsZ and E. coli FtsZ could be shown. The comparison of FtsZ protein structures may also be used for investigation of bacterial phylogenetic relationships. Ó 2002 Elsevier Science (USA). All rights reserved. Keywords: ftsZ Gene; Mycoplasma; M. hominis; Gene expression; Bacterial evolution Taxonomically, Mycoplasma hominis belongs to the class Mollicutes, the smallest cell-wall free prokaryotic organisms. M. hominis has been isolated as a part of the flora of bacterial vaginosis, from the lower genital tract of women [1]. Besides, M. hominis is a common spon- taneous contaminant of eukaryotic cell cultures. Mycoplasmas used to be considered a Clostridial branch ofGrampositiveeubacteriaandweresupposedtolosea large part of genomic material and metabolic pathways during their evolution [2,3]. FtsZ protein plays a pivotal role in bacterial cell division process [4]. FtsZ is widely conservative, so the corresponding genes were found in all eubacterial groups, including Mollicutes, several archebacteria (Ar- chea), and in chloroplasts of plants [5]. But three exceptions have been discovered recently: ftsZ genes were not revealed in the completely sequenced genomes of Chlamidia trachomatis [6], archebacteria Aeropyrum pernix [7], and Ureaplasma urealyticum [8]. So far it is not yet clear as to what other proteins perform the function of FtsZ in these microorganisms. About 15 genes and corresponding proteins are responsible for the division process in Escherichia coli, but only three genes (ftsH,Y,Z) of the division and cell-wall (dcw) group were found in the completely sequenced genomes of Mycoplasma genitalium, Mycoplasma pneumoniae [9,10], and Mycoplasma pulmonis [11]. Functions of ftsH and ftsY gene products in bacterial proliferation are unknown. Polymerization of FtsZ into cytokinetic ring at the predivision site is considered the earliest event of the prokaryotic cell division process. The FtsZ protein has GTPase activity [12], and in vitro it forms filaments similar to those of tubulin [13]. Like eukaryotic tubu- lins, FtsZ proteins have a conservative N-terminal part, a GTP-binding motive, and a comparatively variable hydrophilic C-terminal region. The similarity was Biochemical and Biophysical Research Communications 293 (2002) 155–162 www.academicpress.com * Corresponding author. Fax: +34-91-397-80-87. E-mail address: jayala@cbm.uam.es (J.A. Ayala). 0006-291X/02/$ - see front matter Ó 2002 Elsevier Science (USA). All rights reserved. PII:S0006-291X(02)00184-5