Using biochemical, immunochemical, ultrastructural, genetic and molecular approaches, work from my laboratory has demonstrated that the ICM and cytoplasmic membrane are continuous and that when triggered by environmental stimuli, the ICM arises from invagination and differentiation of the cytoplasmic membrane. The pigment-binding proteins are required for ICM formation. We have cloned the genes encoding the pigment-binding proteins, made mutants in vitro , and evaluated the effects of these mutations in vivo . These studies demonstrated that these proteins are required for ICM formation and has led to the hypothesis that insertion of these proteins in the membrane is a stimulus for membrane proliferation. We are currently evaluating the role of structural aspects of these proteins in membrane biogenesis .
Methanotrophic bacteria use methane as a sole source of carbon and energy.
These organisms have attracted a great deal of interest because as methane consumers, they serve as a methane sink in the environment. In addition, because some of the enzymes of methane metabolism show a very broad substrate specificity, methanotrophs have significant potential in biotechnology including bioremediation. We have developed PCR-based methods to detect methanotrophs and other bacteria in environmental samples. The ICM of methanotrophs has a role in the metabolism of one carbon compounds. This is evidenced by the localization of an enzyme of methane metabolism to the ICM by immunoelectron microscopy.