Crosstalk between the HpArsRS two-component system and HpNikR is necessary for maximal activation of urease transcription

Helicobacter pylori NikR (HpNikR) is a nickel dependent transcription factor that directly regulates a number of genes in this important gastric pathogen. One key gene that is regulated by HpNikR is ureA, which encodes for the urease enzyme. In vitro DNA binding studies of HpNikR with the ureA promoter (P-ureA) previously identified a recognition site that is required for high affinity protein/DNA binding. As a means to determine the in vivo significance of this recognition site and to identify the key DNA sequence determinants required for ureA transcription, herein, we have translated these in vitro results to analysis directly within H. pylori. Using a series of GFP reporter constructs in which the P-ureA DNA target was altered, in combination with mutant H. pylori strains deficient in key regulatory proteins, we confirmed the importance of the previously identified HpNikR recognition sequence for HpNikR-dependent ureA transcription. Moreover, we identified a second factor, the HpArsRS two-component system that was required for maximum transcription of ureA. While HpArsRS is known to regulate ureA in response to acid shock, it was previously thought to function independently of HpNikR and to have no role at neutral pH. However, our qPCR analysis of ureA expression in wildtype, Delta nikR and Delta arsS single mutants as well as a Delta arsS/nikR double mutant strain background showed reduced basal level expression of ureA when arsS was absent. Additionally, we determined that both HpNikR and HpArsRS were necessary for maximal expression of ureA under nickel, low pH and combined nickel and low pH stresses. In vitro studies of HpArsR-P with the P-ureA DNA target using florescence anisotropy confirmed a direct protein/DNA binding interaction. Together, these data support a model in which HpArsRS and HpNikR cooperatively interact to regulate ureA transcription under various environmental conditions. This is the first time that direct cross-talk between HpArsRS and HpNikR at neutral pH has been demonstrated

Polymorphisms of the acid sensing histidine kinase gene arsS in Helicobacter pylori populations from anatomically distinct gastric sites

Phase variation is frequently utilized by bacterial species to affect gene expression such that phenotypic variants are maintained within populations, ensuring survival as environmental or host conditions change. Unusual among Helicobacter pylori phase variable or contingency genes is arsS, encoding a sensory histidine kinase involved in the acid acclimation of the organism. The presence of a 3\u27 homopolymeric cytosine tract of variable length in arsS among Helicobacter pylori strains allows for the expression of various functional ArsS isoforms, differing in carboxy-terminal protein domains. In this study, we analyzed this 3\u27 arsS region via amplified fragment length polymorphism (AFLP) and sequencing analyses for H. pylori populations from 3 different gastric sites of 12 patients. Our data indicate the presence of multiple arsS alleles within each population of H. pylori derived from the gastric antrum, cardia, or corpus of these patients. We also show that H. pylori, derived from the same anatomical site and patient, are predicted to express multiple ArsS isoforms in each population investigated. Furthermore, we identify a polymorphic deletion within arsS that generates another alternate ArsS C-terminal end. These findings suggest that four C-terminal variations of ArsS adds to the complexity of the ArsRS acid adaptation mechanism as a whole and may influence the ability of H. pylori to persist in the gastric niche for decades. (c) 2012 Elsevier Ltd. All rights reserved

The Grizzly, March 19, 1990

Long Awaited Art Minor Develops • Debate Provokes Thought • Fire: Alarming! • Letters: Reminiscent of Nostalgia?; Ex-Editors Thanked • Global Changes In U.N. • Liberal Studies For Freshmen • New Exhibit Opens: Cohen, Zucker at Berman Art Museum • Bear Pack Set For Outdoor Season • Bears: New and Better • Sorry, No Cigar • UC Tennis • Women\u27s Lax Triumph • Video Review • Green Pledgehttps://digitalcommons.ursinus.edu/grizzlynews/1254/thumbnail.jp

Repetitive Sequence Variations in the Promoter Region of the Adhesin-Encoding Gene sabA of Helicobacter pylori Affect Transcription

The pathogenesis of diseases elicited by the gastric pathogen Helicobacter pylori is partially determined by the effectiveness of adaptation to the variably acidic environment of the host stomach. Adaptation includes appropriate adherence to the gastric epithelium via outer membrane protein adhesins such as SabA. The expression of sabA is subject to regulation via phase variation in the promoter and coding regions as well as repression by the two-component system ArsRS. In this study, we investigated the role of a homopolymeric thymine [poly(T)] tract -50 to -33 relative to the sabA transcriptional start site in H. pylori strain J99. We quantified sabA expression in H. pylori J99 by quantitative reverse transcription-PCR (RT-PCR), demonstrating significant changes in sabA expression associated with experimental manipulations of poly(T) tract length. Mimicking the length increase of this tract by adding adenines instead of thymines had similar effects, while the addition of other nucleotides failed to affect sabA expression in the same manner. We hypothesize that modification of the poly(T) tract changes DNA topology, affecting regulatory protein interaction(s) or RNA polymerase binding efficiency. Additionally, we characterized the interaction between the sabA promoter region and ArsR, a response regulator affecting sabA expression. Using recombinant ArsR in electrophoretic mobility shift assays (EMSA), we localized binding to a sequence with partial dyad symmetry -20 and +38 relative to the sabA + 1 site. The control of sabA expression by both ArsRS and phase variation at two distinct repeat regions suggests the control of sabA expression is both complex and vital to H. pylori infection

The Grizzly, September 28, 1989

Berman Art Center Ready to Roll • New Forum Frontier to be Forged • Letter: Granite Windows Grosses Grad • Stern Happy at Ursinus • Bear Pack Run: Join Us! • Bush Wacked at Drug Dialog • Security New Park Patrol • Wellness Days! • Crutcher Leads Lady Bears to Win • Ursinus Nipped by WMC • Soccer: So-So • V-ball: Optimistic View • Athletes of the Week • Hallinger Competes on Wheels • Calliope Blast from Pasthttps://digitalcommons.ursinus.edu/grizzlynews/1242/thumbnail.jp

The Grizzly, October 23, 1987

Middle States to Evaluate the Ursinus Community • Gilmore Tops Successful Homecoming • Greek Life Threatened • Letters: Pledging Restrictions Destructive?; Professor Supports Religious Understanding • Hot Entertainment to Hit Ursinus • As We Begin the World • Dance Forum Dazzles Audience • Scholars Offer Variety • Old Wine in New Bottles • Speech Exam Offered • Surf\u27s Up for the Lady Bears • Ursinus Athletes and Coach Win at Homecoming • This Run\u27s for you Vince • Athlete of the Week: Football\u27s Glenn Worgan • Grizzlies to Hang Tough • Choral Groups to Entertain Ursinus • WVOU is Back! • Ritter Center: A Beehive of Busyness the Busie Body to Premiere Oct. 29 • Owners Strike Backhttps://digitalcommons.ursinus.edu/grizzlynews/1197/thumbnail.jp

The Grizzly, March 3, 1989

Quad Asbestos Cover-Up? • UC Lip-synching Talents Shown at Airband • Letters: Klee Clears Clutter; Fondots Tepid About Water; Students Concerned • Bond is Back! • Isaac\u27s Astounds Aussie • Men\u27s Indoor Ready for Mainstream • Youthful Bears Swim to 3rd • Senior Trio Leads Ursinus • McGowan\u27s Courage Inspiring • Bears End Season Upbeat • Send North Up The River?https://digitalcommons.ursinus.edu/grizzlynews/1231/thumbnail.jp

The Grizzly, February 5, 1988

Cavorting Cop Caught • Lewis Disclaims Labels at Forum • Rock\u27N America • Patterns Campaign Nears Completion • Hockey Held as Hokey • Contra-versial Censorship Irks Student • History Department Interviews a New Way • Concert Features Christian Music • Summer Study in France a Fun-do • Notes: R.A. Rap Session Announced; Presidency Probers Convene; ALF Re-runs Rewarding; Child Safety Course Offered • Men\u27s Hoopsters Suffer Temporary Setback • Track Team Making Great Strides • Record Books Rewritten • U.C. Matters: Wrestling Tough and Confident • Men \u27Mers Holding Their Ownhttps://digitalcommons.ursinus.edu/grizzlynews/1203/thumbnail.jp

The Grizzly, September 8, 1989

Hudson Gets $ Flowing • Earth Day Seed Planted • French Studies Papa\u27s Notes • Lopez Lures Listeners • Kruse Spot to Dawleys House • Presidential Candidates • Victory at GB Classic • Captains Lead Attack • Gros Sets Goals • Quest Continues • V-ball: Ichiban! • Coaches Added • Optimistic Lady Bears Start Season • Beaches No Bumshttps://digitalcommons.ursinus.edu/grizzlynews/1239/thumbnail.jp

The Grizzly, October 7, 1988

Berman Art Center Breaks Ground • Pledging Undergoes Changes • Welcome Home Alumni! • Letter: Honor Code Discussion Revived • Giving Garbage the Dump • Jazz: Basie Style • Ursinus Presents: A Voice of My Own • On the Forum Front • Mistake Free Bears Get First Win • Field Hockey Making Gains • Soccer Gains Respect • Annual Run Offers Health and Fun • 1988 Homecoming Queen Candidates • Sherman Strutting Stuff • Intramural Results Announced • U.C. Welcomes Gilbert\u27s Enthusiasm • Cycling Club Returns • Campbell: Not Your Typical Bowl of Soup • Econ: Economopolis • Professor LoBue Introduces New Chemistry in Pfahler • Discover Discover! • U.C. Students Study Better Late Than Neverhttps://digitalcommons.ursinus.edu/grizzlynews/1219/thumbnail.jp