title: The nucleoid-associated protein HUβ affects global gene expression in Porphyromonas gingivalis.
abstract: HU is a non-sequence-specific DNA-binding protein and one of the most abundant nucleoid-associated proteins in the bacterial cell. Like Escherichia coli, the genome of Porphyromonas gingivalis is predicted to encode both the HUα (PG1258) and the HUβ (PG0121) subunit. We have previously reported that PG0121 encodes a non-specific DNA-binding protein and that PG0121 is co-transcribed with the K-antigen capsule synthesis operon. We also reported that deletion of PG0121 resulted in downregulation of capsule operon expression and produced a P. gingivalis strain that is phenotypically deficient in surface polysaccharide production. Here, we show through complementation experiments in an E. coli MG1655 hupAB double mutant strain that PG0121 encodes a functional HU homologue. Microarray and quantitative RT-PCR analysis were used to further investigate global transcriptional regulation by HUβ using comparative expression profiling of the PG0121 (HUβ) mutant strain to the parent strain, W83. Our analysis determined that expression of genes encoding proteins involved in a variety of biological functions, including iron acquisition, cell division and translation, as well as a number of predicted nucleoid associated proteins were altered in the PG0121 mutant. Phenotypic and quantitative real-time-PCR (qRT-PCR) analyses determined that under iron-limiting growth conditions, cell division and viability were defective in the PG0121 mutant. Collectively, our studies show that PG0121 does indeed encode a functional HU homologue, and HUβ has global regulatory functions in P. gingivalis; it affects not only production of capsular polysaccharides but also expression of genes involved in basic functions, such as cell wall synthesis, cell division and iron uptake.
authors.affiliation: Department of Oral Medicine Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA.|Department of Molecular Genetics, The Forsyth Institute, Cambridge, MA, USA.
authors.forename: Richa
authors.initials: R
authors.lastname: Priyadarshini
authors.affiliation: Department of Oral Medicine Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA.|Department of Molecular Genetics, The Forsyth Institute, Cambridge, MA, USA.
authors.forename: Carla
authors.initials: C
authors.lastname: Cugini
authors.affiliation: Institute of Microbiology and Biotechnology, University of Ulm, Ulm, Germany.
authors.forename: Annette
authors.initials: A
authors.lastname: Arndt
authors.affiliation: Department of Oral Medicine Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA.|Department of Molecular Genetics, The Forsyth Institute, Cambridge, MA, USA.
authors.forename: Tsute
authors.initials: T
authors.lastname: Chen
authors.affiliation: Division of Biomedical Sciences, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, USA.
authors.forename: Natalia O
authors.initials: NO
authors.lastname: Tjokro
authors.affiliation: Division of Biomedical Sciences, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, USA.
authors.forename: Steven D
authors.initials: SD
authors.lastname: Goodman
authors.affiliation: Department of Oral Medicine Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA.|Department of Molecular Genetics, The Forsyth Institute, Cambridge, MA, USA.
authors.forename: Mary E
authors.initials: ME
authors.lastname: Davey
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D046228:Microarray Analysis; D016966:Porphyromonas gingivalis / Q000235:genetics* / Q000378:metabolism*; D011485:Protein Binding; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C040330:histone-like protein HU, bacteria