scholarly journals HmbR, a Hemoglobin-Binding Outer Membrane Protein of Neisseria meningitidis, Undergoes Phase Variation

1999 ◽  
Vol 181 (7) ◽  
pp. 2067-2074 ◽  
Author(s):  
Anthony R. Richardson ◽  
Igor Stojiljkovic
Keyword(s):  
Membrane Protein ◽  
Neisseria Meningitidis ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Phase Variation ◽  
Membrane Receptors ◽  
Phenotypic Switch ◽  
Reading Frame ◽  
Single Colony ◽  
Hemoglobin Binding

ABSTRACT Neisseria meningitidis uses hemoglobin (Hb) as an iron source via two TonB-dependent outer membrane receptors, HmbR and HpuB. Analysis of 25 epidemiologically unrelated clinical isolates from serogroups A, B, C, and Y revealed that 64% strains possessed both Hb receptor genes. Examination of the hmbR expression pattern in strains in which the hpuB gene was genetically inactivated revealed two distinct Hb utilization phenotypes. Five strains retained the ability to grow as a confluent lawn, while seven grew only as single colonies around Hb discs. The single-colony phenotype observed for some hpuB mutants is suggestive of phase variation of hmbR. The length of the poly(G) tract starting at position +1164 of hmbR absolutely correlated with the two Hb utilization phenotypes. All five strains that grew as confluent lawns around Hb discs possessed either 9 or 12 consecutive G residues. All seven strains that grew as single colonies around Hb discs had poly(G) tracts of a length other than 9 or 12. These single-colony variants that arose around the Hb discs had poly(G) tracts with either 9 or 12 consecutive G residues restoring thehmbR reading frame. Inactivation of hmbR in these strains resulted in a loss of Hb utilization, demonstrating that the change in the hmbR gene was responsible for the phenotypic switch. The switching rates from hmbR phase off to phase on were ∼5 × 10−4 in four serogroup C strains, 2 × 10−2 in the serogroup A isolate, and 7 × 10−6 in the serogroup B isolate.

scholarly journals Phase Variation of PorA, a Major Outer Membrane Protein, Mediates Escape of Bactericidal Antibodies by Neisseria meningitidis

2013 ◽  
Vol 81 (4) ◽  
pp. 1374-1380 ◽  
Author(s):  
Isfahan Tauseef ◽  
Youssif M. Ali ◽  
Christopher D. Bayliss
Keyword(s):  
Membrane Protein ◽  
Neisseria Meningitidis ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Outer Membrane Proteins ◽  
Phase Variation ◽  
Surface Expression ◽  
Content Type ◽  
Repeat Tract ◽  
Fold Reduction

ABSTRACTSeveral outer membrane proteins ofNeisseria meningitidisare subject to phase variation due to alterations in simple sequence repeat tracts. The PorA protein is a major outer membrane protein and a target for protective host immune responses. Phase variation of PorA is mediated by a poly-G repeat tract present within the promoter, leading to alterations in protein expression levels.N. meningitidisstrain 8047 was subjected to serial passage in the presence of P1.2, a PorA-specific bactericidal monoclonal antibody. Rapid development of resistance to bactericidal activity was associated with a switch in the PorA repeat tract from 11G to 10G. Phase variants with a 10G repeat tract exhibited a 2-fold reduction in surface expression of PorA protein. AmutSmutant of strain 8047, with an elevated phase variation rate, exhibited a higher rate of escape and an association of escape with 10G and 9G variants, the latter having a 13-fold reduction in surface expression of PorA. We conclude that graduated reductions in the surface expression of outer membrane proteins mediated by phase variation enable meningococci to escape killingin vitroby bactericidal antibodies. These findings indicate how phase variation could have a major impact on immune escape and host persistence of meningococci.

scholarly journals Use of transformation to construct antigenic hybrids of the class 1 outer membrane protein in Neisseria meningitidis.

1993 ◽  
Vol 61 (10) ◽  
pp. 4217-4224 ◽  
Author(s):  
P van der Ley ◽  
J van der Biezen ◽  
P Hohenstein ◽  
C Peeters ◽  
J T Poolman
Keyword(s):  
Membrane Protein ◽  
Neisseria Meningitidis ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Class 1

scholarly journals Identification by Subtractive Hybridization of a Novel Insertion Sequence Specific for Virulent Strains ofPorphyromonas gingivalis

1999 ◽  
Vol 67 (11) ◽  
pp. 5621-5625 ◽  
Author(s):  
Koichi Sawada ◽  
Susumu Kokeguchi ◽  
Hiroshi Hongyo ◽  
Satoko Sawada ◽  
Manabu Miyamoto ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Subtractive Hybridization ◽  
Open Reading Frame ◽  
Specific Marker ◽  
Avirulent Strain ◽  
Target Sequence ◽  
Dna Fragments ◽  
Reading Frame

ABSTRACT Subtractive hybridization was employed to isolate specific genes from virulent Porphyromonas gingivalis strains that are possibly related to abscess formation. The genomic DNA from the virulent strain P. gingivalis W83 was subtracted with DNA from the avirulent strain ATCC 33277. Three clones unique to strain W83 were isolated and sequenced. The cloned DNA fragments were 885, 369, and 132 bp and had slight homology with only Bacillus stearothermophilus IS5377, which is a putative transposase. The regions flanking the cloned DNA fragments were isolated and sequenced, and the gene structure around the clones was revealed. These three clones were located side-by-side in a gene reported as an outer membrane protein. The three clones interrupt the open reading frame of the outer membrane protein gene. This inserted DNA, consisting of three isolated clones, was designated IS1598, which was 1,396 bp (i.e., a 1,158-bp open reading frame) in length and was flanked by 16-bp terminal inverted repeats and a 9-bp duplicated target sequence. IS1598 was detected inP. gingivalis W83, W50, and FDC 381 by Southern hybridization. All three P. gingivalis strains have been shown to possess abscess-forming ability in animal models. However, IS1598 was not detected in avirulent strains of P. gingivalis, including ATCC 33277. The IS1598 may interrupt the synthesis of the outer membrane protein, resulting in changes in the structure of the bacterial outer membrane. The IS1598 isolated in this study is a novel insertion element which might be a specific marker for virulent P. gingivalisstrains.

scholarly journals Characterization of Outer Membrane Proteins in Chlamydia trachomatis LGV Serovar L2

2001 ◽  
Vol 183 (8) ◽  
pp. 2686-2690 ◽  
Author(s):  
Regina J. Tanzer ◽  
Thomas P. Hatch
Keyword(s):  
Chlamydia Trachomatis ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Outer Membrane Proteins ◽  
Major Outer Membrane Protein ◽  
Developmental Cycle ◽  
Reading Frame

ABSTRACT We used a photoactivatable, lipophilic reagent, 3′-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine, to label proteins in the outer membrane of elementary bodies ofChlamydia trachomatis LGV serovar L2 and mass spectrometry to identify the labeled proteins. The identified proteins were polymorphic outer membrane proteins E, G, and H, which were made late in the developmental cycle, the major outer membrane protein, and a mixture of 46-kDa proteins consisting of the open reading frame 623 protein and possibly a modified form of the major outer membrane protein.

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