The DNA-Binding Protein HU has a Regulatory Role in the Acid Stress Response Mechanism in Helicobacter pyloriReport as inadecuate

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Background: Bacterial genomes are compacted by association with histonelikeproteins to form a complex known as bacterial chromatin. The histonelikeprotein HU is capable of binding and bending the DNA molecule, afunction related to compaction, protection, and regulation of gene expression.In Helicobacter pylori, HU is the only histone-like protein described sofar. Proteomic analysis from our laboratory showed that this protein is overexpressedunder acidic stress.Materials and Methods: We used a purified recombinant wild-type proteinand two mutant proteins with the amino acid substitutions K3A-S27D andK62R-V63N-P64A to characterize the function of the N-terminal domainand the flexible arm of HU.Results: In vitro assays for DNA protection, bending, and compaction wereperformed. We also designed a H. pylori hup::cat mutant strain to study therole of HU in the acid stress response. HUwt protein binds DNA and promotesits bending and compaction. Compared with the wild-type protein, bothmutant proteins have less affinity for DNA and an impaired bending andcompaction ability. By using qRT-PCR, we confirmed overexpression oftwo genes related to acid stress response ureA and speA. Such overexpressionwas abolished in the hup::cat strain, which shows an acid-sensitivephenotype.Conclusions: Altogether, we have shown that HUwt–DNA complex formationis favored under acidic pH and that the complex protects DNA fromendonucleolytic cleavage and oxidative stress damage. We also showed thatthe amino-terminal domain of HU is relevant to DNA–protein complexformation and that the flexible arm of HU is involved in the bending andcompaction activities of HU.Nota general

Artículo de publicación ISI

Author: Almarza, Oscar; - Núñez, Daniel; - Toledo Araya, Héctor; -



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