We study regulation of gene expression in a variety of microbes, particularly under conditions of environmental stress. Our main focus is the role of genomic intervening sequences in this process. Our work is highly interdisciplinary, invoking genetics, biochemistry, structural biology, chemical engineering and infectious disease.
First, we study the biology of introns, dynamic sequences that interrupt genes and can therefore disrupt the flow of genetic information. The work runs the gamut from answering fundamental questions about how introns function and how they are removed to preserve genetic integrity, through how introns might have evolved, to ways in which they could be exploited in biotechnology. Introns exist in almost all life forms, from simple bacteria (our own discovery) to more complex species, including humans. Introns are removed from the RNA by a process called splicing. The introns we study are self-splicing; they are themselves the enzymes, called ribozymes, that catalyze splicing. The introns also can move at the level of the DNA, acting as mobile genetic elements. Both the RNA splicing and the DNA mobility mechanisms are examined, as are the proteins that assist these reactions. These studies are based on genetic and biochemical analyses, as well as collaborative structural approaches involving X-ray crystallography, NMR and cryo-electron microscopy. Different introns can move either by a DNA-based double-strand break repair mechanism or via an RNA intermediate in a process termed “retromobility”. These latter introns resemble retroviruses and retrotransposons, raising important evolutionary questions on the orgins of all these elements, while this finding raises the possibility of using introns as delivery vehicles for gene therapy.
Second, unraveling the structure and function of inteins, a type of intervening sequence that is remarkable for splicing at the protein level, is another focus of the Belfort laboratory. Their practical applications are being explored too, and we hold patents for the use of both introns and inteins in biotechnology. Both elements can be used to facilitate protein purification and as biosensors, while inteins, which are found in critical genes of human microbial pathogens, are promising targets for identification of novel antibiotics. Developing intein-based anti-tuberculosis drugs and understanding the role of inteins in TB infection and pathogenesis are current interests of the laboratory.