Determining the function of the Synechococcus elongatus PCC 7942 O‐GlcNAc transferase (791.1)

Abstract

O‐GlcNAc modification, the posttranslational addition of a single O‐linked β‐N‐acetylglucosamine (O‐GlcNAc) to a serine and/or threonine, regulates many processes in plants and animals. Although O‐GlcNAc transferases (OGTs) are predicted to exist in many bacteria species, the function of these OGTs is largely unknown. When the OGT of the photosynthetic cyanobacterium Synechococcus elongatus PCC 7942 was deleted the resulting mutant was viable and had no growth rate defects. The mutant however did have several defects, including cell aggregation that led to the cell settling out of culture, higher free cellular phosphate levels and altered organization of both thylakoids and polyphosphate bodies. These phenotypes were rescued by re‐introduction of the wild‐type OGT, but were not fully rescued by OGTs with mutations affecting the predicted catalytic domain indicating the phenotypes are due to deletion of the OGT. During the course of this research a mutant that was suppressed for the settling phenotype arose spontaneously. Whole genome sequencing has identified a single new mutation in this strain and experiments are underway to determine if this mutation is responsible for suppression of the settling phenotype and to determine if it affects the other phenotypes associated with deletion of the OGT.