Persistent Link:
http://hdl.handle.net/10150/195515
Title:
Novel Pili of Mycobacterium tuberculosis
Author:
Alteri, Christopher
Issue Date:
2005
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Mycobacterium tuberculosis is responsible for nearly three million human deaths every year. Understanding the mechanisms and bacterial factors responsible for M. tuberculosis' ability to cause disease in humans is critical for the development of improved treatment strategies. Using negative staining and transmission electron microscopy it was discovered that mycobacteria, including the human pathogen M. tuberculosis, produce fine surface structures known as pili. Mass spectroscopy analysis demonstrated that purified pili from M. tuberculosis are comprised of protein subunits encoded by the predicted M. tuberculosis H37Rv ORF designated Rv3312A. These pili termed M. tuberculosis pili, Mtp, are highly aggregative 2-5 nm diameter fibers and are recognized by IgG antibodies contained within TB patient sera. These results indicate that Mtp are produced during human infection. Mtp bind to the extracellualr matrix protein laminin in vitro suggesting that Mtp are a newly identified adherence factor for M. tuberculosis.A second pili morphotype that appeared as rope-like bundles were observed for M. tuberculosis and it was found that the M. tuberculosis chromosome contains a type IVB pili gene cluster. The M. tuberculosis type IV pili belong to the Flp sub-family of type IVB pili. RT-PCR analysis reveals that flp is expressed by M. tuberculosis and IF microscopy with Flp-specific antibodies shows the Flp protein is secreted from the bacteria. Evidence presented herein also demonstrates that an Flp-derived peptide is capable of polymerizing into pili-like fibers in vitro over a pH range of 4.5-7.5. Further studies show that the M. tuberculosis type IV pili are encoded by a novel 5-kb genomic island that contains the flp prepilin and putative biogenesis genes. The flp genomic island is characterized by an increased G+C content of 70% (the mean G+C content of the M. tuberculosis chromosome is 65%) and is flanked by multiple direct repeats. The identification of type IV pili in M. tuberculosis is the first report of any classical virulence factor for the bacillus and the genetic characteristics of the locus strongly suggest this chromosomal region was horizontally acquired.
Type:
text; Electronic Dissertation
Keywords:
mycobacteria; tuberculosis; pili; adherence; pathogenesis
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Microbiology & Immunology; Graduate College
Degree Grantor:
University of Arizona
Committee Chair:
Friedman, Richard L.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleNovel Pili of Mycobacterium tuberculosisen_US
dc.creatorAlteri, Christopheren_US
dc.contributor.authorAlteri, Christopheren_US
dc.date.issued2005en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractMycobacterium tuberculosis is responsible for nearly three million human deaths every year. Understanding the mechanisms and bacterial factors responsible for M. tuberculosis' ability to cause disease in humans is critical for the development of improved treatment strategies. Using negative staining and transmission electron microscopy it was discovered that mycobacteria, including the human pathogen M. tuberculosis, produce fine surface structures known as pili. Mass spectroscopy analysis demonstrated that purified pili from M. tuberculosis are comprised of protein subunits encoded by the predicted M. tuberculosis H37Rv ORF designated Rv3312A. These pili termed M. tuberculosis pili, Mtp, are highly aggregative 2-5 nm diameter fibers and are recognized by IgG antibodies contained within TB patient sera. These results indicate that Mtp are produced during human infection. Mtp bind to the extracellualr matrix protein laminin in vitro suggesting that Mtp are a newly identified adherence factor for M. tuberculosis.A second pili morphotype that appeared as rope-like bundles were observed for M. tuberculosis and it was found that the M. tuberculosis chromosome contains a type IVB pili gene cluster. The M. tuberculosis type IV pili belong to the Flp sub-family of type IVB pili. RT-PCR analysis reveals that flp is expressed by M. tuberculosis and IF microscopy with Flp-specific antibodies shows the Flp protein is secreted from the bacteria. Evidence presented herein also demonstrates that an Flp-derived peptide is capable of polymerizing into pili-like fibers in vitro over a pH range of 4.5-7.5. Further studies show that the M. tuberculosis type IV pili are encoded by a novel 5-kb genomic island that contains the flp prepilin and putative biogenesis genes. The flp genomic island is characterized by an increased G+C content of 70% (the mean G+C content of the M. tuberculosis chromosome is 65%) and is flanked by multiple direct repeats. The identification of type IV pili in M. tuberculosis is the first report of any classical virulence factor for the bacillus and the genetic characteristics of the locus strongly suggest this chromosomal region was horizontally acquired.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectmycobacteriaen_US
dc.subjecttuberculosisen_US
dc.subjectpilien_US
dc.subjectadherenceen_US
dc.subjectpathogenesisen_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineMicrobiology & Immunologyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.chairFriedman, Richard L.en_US
dc.contributor.committeememberGiron, Jorge A.en_US
dc.contributor.committeememberJoens, Lynn S.en_US
dc.contributor.committeememberFane, Bentley A.en_US
dc.contributor.committeememberBrown, Judith K.en_US
dc.identifier.proquest1276en_US
dc.identifier.oclc137354761en_US
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