Characterization of the cell wall and cell wall proteins of Chromatium vinosum

Abstract

Highly purified cell walls of Chromatium vinosum were isolated by differential centrifugation, with or without Triton X-100 extraction. The isolated material had a protein composition similar to that of cell walls obtained by sucrose density gradient centrifugation. Twenty-two proteins were reproducibly detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A 42-kilodalton protein was shown to account for 65% of the total cell wall protein. The majority of cell wall proteins were solubilized in sodium dodecyl sulfate at room temperature; however, they existed as high-molecular-weight complexes unless heated to 450C or above. The cell wall contained one heat-modifiable protein which migrated with an apparent molecular weight of 37,400 when solubilized at 700C or below, but which migrated with an apparent molecular weight of 52,500 if solubilized at 1000C. The electrophoretic mobility of three proteins was modified by 2-mercaptoethanol. The majority of C. vinosum cell wall proteins had isoelectric points between pH 4.5 and 5.5, and the 42-kilodalton protein focused at pH 4.9. No proteins were detected which were analogous to the lipoprotein or peptidoglycanassociated proteins of the Enterobacteriaceae. Nearest-neighbor analysis with a reducible, cross-linking reagent indicated that three proteins, including the 42kilodalton protein, associated with themselves. Most of the cell wall proteins were partially accessible to proteases in both intact cells and isolated cell walls. Protease treatment of the whole cell or isolated cell wall digested approximately an 11,000-molecular-weight portion of the 42-kilodalton protein.

Characterization of Tn 5 -Induced Mutants of Xenorhabdus nematophilus ATCC 19061

“…Comparison of the total cellular protein-banding pattern of X. nematophilus ATCC 19061/1 wild type with avirulent TnS mutants. Cells were grown for 20 to 24 h at 28°C with shaking in 1.5 ml of LB; pelleted in a microcentrifuge for 5 min; suspended in the original volume of sterile, deionized water; and used for sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis as previously described (24). The proteins (in 20-,ul volumes) were separated on a 1.5-mm-thick 12% acrylamide gel and stained with Coomassie brilliant blue R. Lane 1, X. nematophilus ATCC 19061/1; lane 2, AV1; lane 3, AVlS (derivative of AV1 resistant to 100 ±ug of streptomycin ml-'); lane 4, 7A-2/1SA; lane 5, 7A-2/1G; lane 6, 7A-2/1SAL (large colony from clonal plating of 7A-2/1SA); lane 7, 7A-2/1SAS (small colony from clonal plating of 7A-2/1SA).…”

Colonial and Cellular Polymorphism in Xenorhabdus luminescens

“…The protein concentration was determined by a modified Folin procedure (27,41). SDS-PAGE was performed as previously described with 12% acrylamide gels (26).…”

Disulfide-Linked Oligomers of the Major Outer Membrane Protein of Chlamydiae

“…The existence of naturally occurring disulfidelinked protein complexes, such as immunoglobulins, is well known. In addition, the presence of disulfide-linked proteins in bacterial outer membranes has also been described (8,17). However, the matrix proteins of gram-negative bacteria, which are similar to the MOMP of chlamydiae in terms of relative abundance, molecular weight, and surface exposure, are not covalently linked to each other.…”