Autocatalytic gene expression occurs via transertion and membrane domain formation and underlies differentiation in bacteria: a model.

When bacteria contain two chromosomes, two or more copies of the same gene are present in the same cytoplasm and, if these copies are subject to negative regulation in trans and positive (autocatalytic) regulation in cis, one copy will be expressed at the expense of the other copy(ies). This autocatalytic process depends on the coupled transcription, or translation and insertion of nascent proteins into the membrane, or transertion. Transertion is responsible for looping genes out of the nucleoid and increasing their accessibility to transcription factors. Transertion of proteins with lipid preferences creates proteolipid domains in the membrane. These domains fuse to give two types of large domains, each associated with the expression of a particular set of genes. These large domains organize kinases, proteases and transcription factors and result in the expression of one set of genes encoding proteins with common lipid preferences from one chromosome and expression of a different set from the other. These intracellular differences underlie the production of different progeny by cell division that follows, for example, reception of extracellular signals, and that constitutes differentiation in bacteria.