Resumen De Artuculo De: La Biología Estructural De Proteínas De Membrana

Gram-negative bacteria, mitochondria, and chloroplasts contain both an inner and outer
membrane. The outer membrane contains numerous β-barrel proteins Commonly calledouter membrane proteins, which serve essential functions in cargo transport and signaling and are also vital for membrane biogenesis. The number of strands
observed in allouter membrane proteins thus far range from 8 to 24, and almost all outer membrane proteins contain an even
number of stands, for example Ail Yersinia pestisadhesin/invasin 3QRA, 3QRC. Despite the common β-barrel scaffold, outer membrane proteins have evolved to perform many different functions including acting as porins, transporters,enzymes, and
receptors. In Gram-negative bacteria, outer membrane proteins are synthesized in the cytoplasm and then transported across the inner membrane and into theperiplasm by the SecYEG translocon. Once in the periplasm, chaperones such as SurA and Skp guide nascent outer membrane proteins across the periplasm and peptidoglycan layer to theinner leaflet of the OM. Here, the nacen outer membrane proteins are recognized by a complex known as the β-barrel assembly machinery (BAM) complex which folds and insertsthe new outer membrane proteins into the outer membrane. The Escherichia coli barrel assembly machinery complex consists of five subunits named barrel assembly machineryB, C, D and E. Although we do not yet understand how the barrel assembly machinery complex functions in detail, studies have shown that barrel assembly machinery A andbarrel assembly machinery D are essential for cell viability and outer membrane protein
biogenesis, while barrel assembly machinery B, C, and E serve regulatory roles.