Major Outer Membrane Protein (major + outer_membrane_protein)

Distribution by Scientific Domains

Selected Abstracts

Characterization and functional analysis of PorB, a Chlamydia porin and neutralizing target

Aya Kubo
A predicted protein (CT713) with weak sequence similarity to the major outer membrane protein (20.4% identity) in Chlamydia trachomatis was identified by Chlamydia genome analysis. We show that this protein is expressed, surface accessible, localized to the chlamydial outer membrane complex and functions as a porin. This protein, PorB, was highly conserved among different serovars, with nearly identical sequences between serovars D, B, C and L2. Sequence comparison between C. trachomatis and Chlamydia pneumoniae showed less conservation between species with 59.3% identity. Immunofluorescence staining with monospecific antisera to purified PorB revealed antigen localized within chlamydial inclusions and found throughout the developmental cycle. Antibodies to PorB neutralized infectivity of C. trachomatis in an in vitro neutralization assay confirming that PorB is surface exposed. As PorB was found to be in the outer membrane, as well as having weak structural characteristics similar to major outer membrane protein (MOMP) and other porins, a liposome-swelling assay was used to determine whether this protein had pore-forming capabilities. PorB had pore-forming activity and was shown to be different from MOMP porin activity. [source]

Proteolytic cleavage of the Chlamydia pneumoniae major outer membrane protein in the absence of Pmp10

Nicolai Juul
Abstract The genome of the obligate intracellular bacteria Chlamydia pneumoniae contains 21 genes encoding polymorphic membrane proteins (Pmp). While no function has yet been attributed to the Pmps, they may be involved in an antigenic variation of the Chlamydia surface. It has previously been demonstrated that Pmp10 is differentially expressed in the C. pneumoniae CWL029 isolate. To evaluate whether the absence of Pmp10 in the outer membrane causes further changes to the C. pneumoniae protein profile, we subcloned the CWL029 isolate and selected a clone with minimal Pmp10 expression. Subsequently, we compared the proteome of the CWL029 isolate with the proteome of the subcloned strain and identified a specific cleavage of the C-terminal part of the major outer membrane protein (MOMP), which occurred only in the absence of Pmp10. In contrast, when Pmp10 was expressed we predominantly observed full-length MOMP. No other proteins appeared to be regulated according to the presence or absence of Pmp10. These results suggest a close association between MOMP and Pmp10, where Pmp10 may protect the C-terminal part of MOMP from proteolytic cleavage. [source]

ORIGINAL ARTICLE: A Multi-Subunit Chlamydial Vaccine Induces Antibody and Cell-Mediated Immunity in Immunized Koalas (Phascolarctos cinereus): Comparison of Three Different Adjuvants

Alison J. Carey
Citation Carey AJ, Timms P, Rawlinson G, Brumm J, Nilsson K, Harris JM, Beagley KW. A multi-subunit chlamydial vaccine induces antibody and cell-mediated immunity in immunized koalas (Phascolarctos cinereus): comparison of three different adjuvants. Am J Reprod Immunol 2010; 63: 161,172 Problem, Chlamydial infections represent a major threat to the survival of the koala. Infections caused by Chlamydia pecorum cause blindness, infertility, pneumonia and urinary tract infections and represent a threat to the survival of the species. Little is known about the immune response in koalas, or the safety of commonly used adjuvants for induction of protective systemic and mucosal immunity. Method of study, In the present study, we immunized 18 healthy female koalas subcutaneously with a combination of three chlamydial antigens [major outer membrane protein (MOMP), NrdB and TC0512 (Omp85)] mixed with one of three different adjuvants [Alhydrogel, Immunostimulating Complex (ISC) and TiterMax Gold]. Results, All adjuvants induced strong neutralizing IgG responses in plasma against the three antigens with prolonged responses lasting more than 270 days seen in Alhydrogel and ISC immunized animals. Cloacal IgG responses lasting >270 days were also induced in ISC-immunized animals. Chlamydia -specific peripheral blood mononuclear cell proliferative responses were elicited by both Alhydrogel and ISC, and these lasted >270 days in the ISC group. Conclusion, The data show that a multi-subunit chlamydial vaccine, given subcutaneously, can elicit Chlamydia -specific cell-mediated and antibody responses in the koala demonstrating that the development of a protective vaccine is feasible. [source]

Crystallization and preliminary crystallographic studies of MOMP (major outer membrane protein) from Campylobacter jejuni

Jean Michel Bolla
Campylobacter jejuni is the leading bacterial cause of human enteritis linked to ingestion of contaminated food or water. MOMP, the major outer membrane protein from these Gram-negative bacteria, belongs to the porin family. In order to determine the three-dimensional structure of this protein and to elucidate the underlying molecular mechanisms, the MOMP from C. jejuni strain 85H has been purified and crystallized by vapour diffusion. Two crystal forms were characterized for this membrane protein. X-ray diffraction data were collected to a resolution of 3.1, using a synchrotron-radiation source from the orthorhombic crystal form, which belonged to space group P21212 with unit-cell parameters a = 170.1, b = 101.9, c = 104.9,. With a trimer in the asymmetric unit, the solvent content is 64% (VM = 3.4,,Da,1). The other form exhibits trigonal symmetry (space group R3) with hexagonal unit-cell parameters a = b = 94.2, c = 161.2,, but diffracts X-rays poorly to about 4, with significant anisotropy. [source]