Assembly and promoter analysis of variant-specific surface protein (vsp) genes of Giardia lamblia

Persistent Link:
http://hdl.handle.net/10150/194194
Title:
Assembly and promoter analysis of variant-specific surface protein (vsp) genes of Giardia lamblia
Author:
Nigam, Anuranjini
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:
Giardia lamblia undergoes antigenic variation of variant-specific surface proteins (VSPs) that are encoded by a family of ~150 vsp genes only one of which is expressed at a time. The vsp gene promoters have not been previously studied. A comparison of the upstream non-coding region of vsp genes shows that they lack the AT-rich regions found in other Giardia gene promoters. We have determined that the core promoters of vsp A6 and vsp C5 genes extend from -57 to + 6 and -50 to + 6 respectively. Through linker scanning analysis, we have also identified regions within the vsp A6 core promoter important for promoter activity that span -7-3, -12-8, -17-13 and -42-38.There is no sequence similarity in the upstream regions of the previously characterized vsp genes that were analyzed, with the exception of a seven nucleotide region that encompasses the translation initiation site: Py A A T G T T. We have demonstrated that the four nucleotides flanking the start codon are essential for promoter activity. This result suggests that it may be an Inr element, which by definition determines the site of transcription initiation. In addition, this element loosely resembles the metazoan Inr consensus: Py Py A A/T Py Py. Using 5′ RACE I have determined that for two vsp genes, the translation and transcription start sites are synonymous and reside within this conserved element. However, we were unable to identify protein factors that bind this region using electrophoretic mobility shift assays.A search for characteristic VSP motifs, such as CRGKA, amongst identified ORFs in the Giardia genome assembly in turn identified 180 ORFs which may be VSPs. Eighty one of these are found within contigs while 99 of these are found at contig and 80 ORFs have the Inr element identified in this study.This study supports the hypothesis that longer upstream non-coding regions of vsp genes play a role in regulating the expression of these genes and hence antigenic variation in G. lamblia.
Type:
text; Electronic Dissertation
Keywords:
Microbiology & Immunology
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Microbiology & Immunology; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Adam, Rodney D.
Committee Chair:
Adam, Rodney D.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleAssembly and promoter analysis of variant-specific surface protein (vsp) genes of Giardia lambliaen_US
dc.creatorNigam, Anuranjinien_US
dc.contributor.authorNigam, Anuranjinien_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.abstractGiardia lamblia undergoes antigenic variation of variant-specific surface proteins (VSPs) that are encoded by a family of ~150 vsp genes only one of which is expressed at a time. The vsp gene promoters have not been previously studied. A comparison of the upstream non-coding region of vsp genes shows that they lack the AT-rich regions found in other Giardia gene promoters. We have determined that the core promoters of vsp A6 and vsp C5 genes extend from -57 to + 6 and -50 to + 6 respectively. Through linker scanning analysis, we have also identified regions within the vsp A6 core promoter important for promoter activity that span -7-3, -12-8, -17-13 and -42-38.There is no sequence similarity in the upstream regions of the previously characterized vsp genes that were analyzed, with the exception of a seven nucleotide region that encompasses the translation initiation site: Py A A T G T T. We have demonstrated that the four nucleotides flanking the start codon are essential for promoter activity. This result suggests that it may be an Inr element, which by definition determines the site of transcription initiation. In addition, this element loosely resembles the metazoan Inr consensus: Py Py A A/T Py Py. Using 5′ RACE I have determined that for two vsp genes, the translation and transcription start sites are synonymous and reside within this conserved element. However, we were unable to identify protein factors that bind this region using electrophoretic mobility shift assays.A search for characteristic VSP motifs, such as CRGKA, amongst identified ORFs in the Giardia genome assembly in turn identified 180 ORFs which may be VSPs. Eighty one of these are found within contigs while 99 of these are found at contig and 80 ORFs have the Inr element identified in this study.This study supports the hypothesis that longer upstream non-coding regions of vsp genes play a role in regulating the expression of these genes and hence antigenic variation in G. lamblia.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectMicrobiology & Immunologyen_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.advisorAdam, Rodney D.en_US
dc.contributor.chairAdam, Rodney D.en_US
dc.contributor.committeememberAhmad, Nafeesen_US
dc.contributor.committeememberPayne, Claireen_US
dc.contributor.committeememberWalsh, Bruceen_US
dc.identifier.proquest1209en_US
dc.identifier.oclc137354384en_US
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