Transcriptional control of central carbon metabolic flux in Bifidobacteria by two functionally similar, yet distinct LacI-type regulators

Abstract

Bifdobacteria resident in the gastrointestinal tract (GIT) are subject to constantly changing environmental conditions, which require rapid adjustments in gene expression. Here, we show that two predicted LacI-type transcription factors (TFs), designated AraQ and MalR1, are involved in regulating the central, carbohydrate-associated metabolic pathway (the so-called phosphoketolase pathway or bifd shunt) of the gut commensal Bifdobacterium breve UCC2003. These TFs appear to not only control transcription of genes involved in the bifd shunt and each other, but also seem to commonly and directly afect transcription of other TF-encoding genes, as well as genes related to uptake and metabolism of various carbohydrates. This complex and interactive network of AraQ/MalR1-mediated gene regulation provides previously unknown insights into the governance of carbon metabolism in bifdobacteria.