Altered morphology produced by ftsZ expression in Corynebacterium glutamicum ATCC 13869

Abstract

Corynebacterium glutamicum is a Gram-positive bacterium that lacks the cell division FtsA protein and actin-like MreB proteins responsible for determining cylindrical cell shape. When the cell division ftsZ gene from C. glutamicum (ftsZ Cg ) was cloned in different multicopy plasmids, the resulting constructions could not be introduced into C. glutamicum; it was assumed that elevated levels of FtsZ Cg result in lethality. The presence of a truncated ftsZ Cg and a complete ftsZ Cg under the control of Plac led to a fourfold reduction in the intracellular levels of FtsZ, generating aberrant cells displaying buds, branches and knots, but no filaments. A 20-fold reduction of the FtsZ level by transformation with a plasmid carrying the Escherichia coli lacI gene dramatically reduced the growth rate of C. glutamicum, and the cells were larger and club-shaped. Immunofluorescence microscopy of FtsZ Cg or visualization of FtsZ Cg -GFP in C. glutamicum revealed that most cells showed one fluorescent band, most likely a ring, at the mid-cell, and some cells showed two fluorescent bands (septa of future daughter cells). When FtsZ Cg -GFP was expressed from Plac, FtsZ rings at mid-cell, or spirals, were also clearly visible in the aberrant cells; however, this morphology was not entirely due to GFP but also to the reduced levels of FtsZ expressed from Plac. Localization of FtsZ at the septum is not negatively regulated by the nucleoid, and therefore the well-known occlusion mechanism seems not to operate in C. glutamicum.

Bacterial Growth and Cell Division: a Mycobacterial Perspective

“…Nucleoid occlusion is not seen in S. coelicolor and C. glutamicum during divisome assembly (164,333,369). Using fluorescence microscopy, the images seem to show overlapping nucleoid staining and FtsZ-green fluorescent protein (GFP) fluorescence; however, it could be that the resolution of such imaging is unable to detect the initiation of chromosome partitioning that may have already begun in the bacteria.…”

“…A 4-fold decrease in FtsZ was found to result in aberrant cells with buds, branches, and knots, but no filaments, while a 20-fold decrease yielded large, club-shaped cells (333). Promoter analysis of the M. tuberculosis ftsZ allele revealed up to six promoters, indicating a high level of transcriptional regulation available as well as the possible need for elevated basal levels of FtsZ in mycobacteria (355).…”

FtsZ and the division of prokaryotic cells and organelles

“…Membrane staining has indicated that certain lipid domains might be enriched at division sites, either as a cause or an effect of Z-ring localization 60 . Alternative factors in ring positioning will probably be important in the many species that lack the Min system, or in species that do not exhibit obvious nucleoid occlusion 61,62 .…”

From the Characterization of the Four Serine/Threonine Protein Kinases (PknA/B/G/L) of Corynebacterium glutamicum toward the Role of PknA and PknB in Cell Division

“…The P gntK promoter is located upstream of the gntK gene encoding the C. glutamicum gluconate kinase and is regulated by sucrose (2). The E. coli P lac promoter allows low expression levels in C. glutamicum (52). In C. glutamicum, pKLA/B and pKPKA/B were unable to replicate autonomously but integrated by homologous recombination into the chromosomal pknA/B locus, respectively.…”