Dimeric Brucella abortus Irr protein controls its own expression and binds haem.
نویسندگان
چکیده
Brucella abortus needs to synthesize haem in order to replicate intracellularly and to produce virulence in mice. Thus, to gain insight into the pathogenesis of the bacterium, regulatory proteins of the haem biosynthetic pathway were sought. An iron response regulator (Irr) from Bradyrhizobium japonicum, which is a close relative of Brucella, was previously described as being involved in the coordination of haem biosynthesis and iron availability. The Bru. abortus genome was searched for an irr orthologue gene, and the Bru. abortus irr gene was cloned, sequenced and disrupted. A null mutant was constructed that accumulated protoporphyrin IX under conditions of iron deprivation. This phenotype was overcome by a complementing plasmid carrying the wild-type irr. Purified recombinant Bru. abortus Irr behaved as a stable dimer and bound haem. Interestingly, in vivo, Irr was only detected in cells obtained from iron-limited cultures and the protein downregulated its own transcription. Through lacZ fusion, it was demonstrated that iron did not regulate irr transcription. The data reported show that Bru. abortus Irr is a homodimeric protein that is accumulated in iron-limited cells, controls its own transcription and downregulates the biosynthesis of haem precursors.
منابع مشابه
High Level Expression of Recombinant Ribosomal Protein (L7/L12) from Brucella abortus and Its Reaction with Infected Human Sera
Brucellosis, caused by Brucella spp., is an important zoonotic disease that causes abortion and infertility in cattle and undulant fever in humans. Various studies have examined cell-free native and recombinant proteins as candidate protective antigens in animal models. Among Brucella immunogenes, antigen based on ribosomal preparation has been widely investigated. In this study, the immunogeni...
متن کاملThe iron-responsive regulator irr is required for wild-type expression of the gene encoding the heme transporter BhuA in Brucella abortus 2308.
Irr and RirA, rather than Fur, serve as the major iron-responsive regulators in the alphaproteobacteria. With only a few exceptions, however, the relative contributions of these transcriptional regulators to the differential expression of specific iron metabolism genes in Brucella strains are unclear. The gene encoding the outer membrane heme transporter BhuA exhibits maximum expression in Bruc...
متن کاملExpression of Brucella abortus Omp25 Protein in Lactococcus lactis Probiotic Bacteria
Background and purpose: The sequence of Omp25 is conserved in all Brucella species. The high antigenicity of the product of this gene stimulates the host’s immune system. Using engineered probiotic bacteria is an appropriate method for vaccine transport. The aim of this study was to express the Omp25 of the Brucella abortus pathogenic bacterium in Lactococcus lactis probiotic bacterium. Materi...
متن کاملThe Importance of Haem vs Non-Haem Iron in the Survival and Pathogenesis of Brucella abortus
متن کامل
Cloning and expression of Brucella outer membrane protein 36kDa (OMP2b) in E. coli
Background & Objective: Brucellosis is an important zoonotic disease of economic significance. Brucella species are gram-negative, facultative intracellular bacteria, and are capable of replicating in the phagosomes of macrophages. They cause infection in several animal species and humans. Prevention of new diseases and diagnosis of cases infected with the organism are both essential for eradic...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Microbiology
دوره 151 Pt 10 شماره
صفحات -
تاریخ انتشار 2005