CIBICI   14215
CENTRO DE INVESTIGACION EN BIOQUIMICA CLINICA E INMUNOLOGIA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
MreD is involved in chromosome segregation of Streptococcus pneumoniae.
Autor/es:
OLIVERO, NADIA; CORTES, PAULO; YANDAR, N.; HERNANDEZ MORFA, MIRELYS; REINOSO-VIZCAINO, NICOLÁS; ECHENIQUE J
Lugar:
Salta
Reunión:
Congreso; LV REUNIÓN ANUAL DE SAIB Y XIV CONGRESO DE LA PABMB; 2019
Institución organizadora:
SAIB-PABMB
Resumen:
The bacterial cell cycle is a highly regulated process in which both division proteins and chromosome have defined spatial and temporal localization patterns. The mechanism that connects these processes is not largely studied so far, particularly in ovococci. It has been proposed that DNA replication initiation coincides with the Z-ring formation in Streptococcus pneumoniae and that proper segregation of the chromosomal origin is crucial for division site selection. However, little is known about the structural support that facilitates the temporal space coordination of these processes. MreB is a bacterial actin-like protein that plays important roles in the determination of cell shape and chromosome segregation in bacteria such as Escherichia coli and Caulobacter crescentus. In these bacteria, MreB forms a membrane-bound complex with MreD and MreC which is essential to maintain cell morphology. S. pneumoniae lacks MreB homologs but presents MreC and MreD, although their functions are not fully known. Similarly to rod-shaped bacteria, the mreCD genes are essential in the virulent serotype 2 D39 strain of S. pneumoniae, and the conditional depletion of MreCD results in cell rounding and lysis. In contrast, the R6 strain contains suppressors that allow the growth of mreCD mutants. In this work, we show that in the Cp1015 strain, the mreC and mreD genes can also be mutated by insertion-duplication mutagenesis resulting in cells with smaller size compared with the wild-type strain, indicating a putative role in the elongasome. Light scattering measurements by flow cytometric analysis displayed that the mreD mutant shows reduced cellular complexity (granular deposits, chromosomal DNA content), in contrast, the mreC mutant showed similar phenotype than the wild-type strain. On the other hand, we observed by epifluorescence microscopy atypical chromosomal segregation in the mreD mutant but not in the mreC strain. We obtained the revertant strains of the mreD mutant and this strain showed phenotypes similar to the wild-type cells. These results suggest that MreD is involved in chromosome segregation and that both MreC and MreD are probably part of the elongasome of S. pneumoniae.