title: Structural insight into the mechanisms of transport across the Salmonella enterica Pdu microcompartment shell.
abstract: Bacterial microcompartments are a functionally diverse group of proteinaceous organelles that confine specific reaction pathways in the cell within a thin protein-based shell. The propanediol utilizing (Pdu) microcompartment contains the reactions for metabolizing 1,2-propanediol in certain enteric bacteria, including Salmonella. The Pdu shell is assembled from a few thousand protein subunits of several different types. Here we report the crystal structures of two key shell proteins, PduA and PduT. The crystal structures offer insights into the mechanisms of Pdu microcompartment assembly and molecular transport across the shell. PduA forms a symmetric homohexamer whose central pore appears tailored for facilitating transport of the 1,2-propanediol substrate. PduT is a novel, tandem domain shell protein that assembles as a pseudohexameric homotrimer. Its structure reveals an unexpected site for binding an [Fe-S] cluster at the center of the PduT pore. The location of a metal redox cofactor in the pore of a shell protein suggests a novel mechanism for either transferring redox equivalents across the shell or for regenerating luminal [Fe-S] clusters.
authors.affiliation: Molecular Biology Institute, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Crowley
authors.forename: Duilio
authors.initials: D
authors.lastname: Cascio
authors.forename: Michael R
authors.initials: MR
authors.lastname: Sawaya
authors.forename: Jeffery S
authors.initials: JS
authors.lastname: Kopstein
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Bobik
authors.forename: Todd O
authors.initials: TO
authors.lastname: Yeates
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001692:Biological Transport; D018360:Crystallography, X-Ray; D008969:Molecular Sequence Data; D015388:Organelles / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011409:Propylene Glycols / Q000378:metabolism*; D019779:Salmonella enterica / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D001426:Bacterial Proteins; C450428:PduA protein, Salmonella enterica; D011409:Propylene Glycols