What is Porb?
Using SWATH-MS, the proteomes of the wild-type strain MC58, the porA-deficient 58DA strain and the double porin-deficient 58DAB strain were compared. The absence of both major porins led to a greater number of changes in protein abundance, presumably reflecting compensation in the expression of other proteins.
We observed upregulation of NMB1963 (part of the glutamine uptake operon), suggesting a role for this protein in general nutrient and energy metabolism. This was accompanied by downregulation of PpsA (phosphoenolpyruvate synthase) and AdhP (aconitate hydratase).
SWATH-MS identified changes in the abundance of 33 proteins (8.3%) in 58DA relative to MC58, including 13 with increased abundance and 14 with decreased abundance. These results support the hypothesis that the major porins play a significant role in the uptake of sugars and amino acids, as well as regulating antibiotic influx.