Analyses of murine GBP homology clusters based on in silico, in vitro and in vivo studies

Alexandra Kresse,Jan Wuerthner,Cornelia Beuter-Gunia,Sandra Beer,Daniel Degrandi,Carolin Konermann,Klaus Pfeffer

doi:10.1186/1471-2164-9-158

Alexandra Kresse, Jan Wuerthner + Show 5 more

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https://doi.org/10.1186/1471-2164-9-158

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Journal: BMC Genomics	Publication Date: Apr 10, 2008
Citations: 93	License type: cc-by

Affiliation: Heinrich Heine University Düsseldorf

Abstract

The interactions between pathogens and hosts lead to a massive upregulation of antimicrobial host effector molecules. Among these, the 65 kDa guanylate binding proteins (GBPs) are interesting candidates as intricate components of the host effector molecule repertoire. Members of the GBP family are highly conserved in vertebrates. Previous reports indicate an antiviral activity of human GBP1 (hGBP1) and murine GBP2 (mGBP2). We recently demonstrated that distinct murine GBP (mGBP) family members are highly upregulated upon Toxoplasma gondii infection and localize around the intracellular protozoa T. gondii. Moreover, we characterised five new mGBP family members within the murine 65 kDa GBP family. Here, we identified a new mGBP locus named mGbp11. Based on bacterial artificial chromosome (BAC), expressed sequence tag (EST), and RT-PCR analyses this study provides a detailed insight into the genomic localization and organization of the mGBPs. These analyses revealed a 166-kb spanning region on chromosome 3 harboring five transcribed mGBPs (mGbp1, mGbp2, mGbp3, mGbp5, and mGbp7) and one pseudogene (pseudomGbp1), as well as a 332-kb spanning region on chromosome 5 consisting of six transcribed mGBPs (mGbp4, mGbp6, mGbp8, mGbp9, mGbp10, and mGbp11), and one pseudogene (pseudomgbp2). Besides the strikingly high homology of 65% to 98% within the coding sequences, the mGBPs on chromosome 5 cluster also exhibit a highly homologous exon-intron structure whereas the mGBP on chromosome 3 reveals a more divergent exon-intron structure. This study details the comprehensive genomic organization of mGBPs and suggests that a continuously changing microbial environment has exerted evolutionary pressure on this gene family leading to multiple gene amplifications. A list of links for this article can be found in the Availability and requirements section.

Highlights

The guanylate binding proteins (GBPs) were first described in 1979 when Gupta et al identified a 67 kDa protein induced in human fibroblasts after interferon γ (IFNγ) stimulation [1]
Based on bacterial artificial chromosome (BAC), expressed sequence tag (EST), and RTPCR analyses this study provides a detailed insight into the genomic localization and organization of the murine GBP (mGBP)
We have demonstrated that mGBPs are highly upregulated in mice after infection with Listeria monocytogenes or Toxoplasma gondii, and localize around the parasitophorous vacuole of T. gondii, suggesting that the mGBPs play a role in the defense against intracellular bacteria and apicomplexa [5]

Summary

Introduction

The guanylate binding proteins (GBPs) were first described in 1979 when Gupta et al identified a 67 kDa protein induced in human fibroblasts after interferon γ (IFNγ) stimulation [1]. Human and murine GBPs possess the unique ability to bind to agarose-immobilized GMP (guanosine monophosphate), GDP (guanosine diphosphate), and GTP (guanosine triphosphate) with the same affinity, thereby differing from heterotrimeric or Ras-like GTP-binding proteins [2]. They hydrolyse GTP to GDP and to GMP [9]. In the case of hGBP1 a nucleotide-dependent oligomerization and concentration-dependent GTPase activity has been observed [11] These biochemical properties classified the GBPs as distantly related family members of the dynamin superfamily despite the lack of any sequence homology of the primary sequences [11,12].

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