The GndA microprotein promotes cell growth during heat shock

Biological functions have been ascribed to an increasing number of microproteins, some of which play roles in bacterial stress responses. In this work, we provide evidence that GndA, a frameshifted 36-amino acid microprotein encoded in an internal open reading frame (intORF) overlapping the 6-phosphogluconate dehydrogenase (6PGD) coding sequence, functions in the response to heat shock.

We demonstrate independent contributions of GndA and 6PGD to cell growth at high temperature. GndA is highly hydrophobic and associates with pyruvate dehydrogenase and respiratory complex I. Consistent with a role in cellular homeostasis, GndA mutations alter the transcriptional responses to heat shock. These results suggest that GndA promotes bacterial cell growth at high temperature via a mechanism distinct from that of the 6PGD protein that it overlaps.