Jan-Willem Veening

jan-willem-180x180Jan-Willem Veening obtained his Ph.D. from the University of Groningen (UG), the Netherlands, and received postdoctoral training at the Centre for Bacterial Cell Biology of Newcastle University in the United Kingdom. 

In 2009, he joined the faculty of the UG, as Assistant Professor in the Molecular Genetics Department of the Groningen Biomolecular Sciences and Biotechnology Institute. In 2016 he moved to the University of Lausanne in Switzerland as full professor at the Department of Fundamental Microbiology. The Veening lab uses systems and synthetic biology approaches to study chromosome segregation, antibiotic resistance development, and noise in gene expression in the pneumococcus. 

Identification of a unique cell cycle regulator in Streptococcus pneumoniae by en masse GFP localization, Tn-seq and CRISPRi phenotyping

Several systems connecting chromosome segregation with division have been identified in model bacteria, but such a cell-cycle regulator has not been identified in Streptococcus pneumoniae. Based on results from transposon-sequencing (Tn-seq), we refined the list of essential genes in S. pneumoniae strain D39. Next, we created a knockdown library targeting 348 potentially essential genes by CRISPR interference (CRISPRi) and show a growth phenotype for 254 of them (73%). Since several general and conserved cell cycle proteins present in the pneumococcus (e.g. EzrA, FtsZ, FtsK) typically localize at mid- cell, we hypothesized that important cell-cycle regulators would have a similar localization pattern. To identify such proteins, we systematically tagged every essential protein of unknown function to a monomeric superfolder-GFP. By combining Tn-Seq, CRISPRi and GFP-localization data, we identified CcrZ (Cell Cycle Regulator protein Z), which co-localizes with FtsZ and is highly conserved in Streptococci. Marker frequency analysis, suppressor analysis and chromosome labeling experiments showed that, in absence of CcrZ, daughter chromosomes are not properly segregated prior to cell division. Together, these findings indicate that CcrZ acts as a link between DNA replication, chromosome segregation and cell division. Future work is aimed at revealing the mechanisms underlying cell-cycle control by CcrZ.