Structural and Functional Studies of Truncated Hemolysin A from Proteus mirabilis

Weaver, Todd; Hocking, Jason; Bailey, L.J.; Wawrzyn, Grayson T.; Howard, Donald; Sikkink, Laura A.; Ramı́rez-Alvarado, Marina; Thompson, James R.

doi:10.1074/jbc.m109.014431

Cited by 35 publications

(42 citation statements)

References 43 publications

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“…This requires sequential unfolding of the HpmA protein (207), for which a partial crystal structure has been solved (208). Two polypeptides, HpmB and HpmA, synthesized in that transcriptional order, are responsible for hemolysin activity of P. mirabilis ( link Toxins section ).…”

Section: Virulence Factorsmentioning

confidence: 99%

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Pathogenesis of Proteus mirabilis Infection

2018

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Proteus mirabilis, a Gram-negative rod-shaped bacterium most noted for its swarming motility and urease activity, frequently causes catheter-associated urinary tract infections (CAUTI) that are often polymicrobial. These infections may be accompanied by urolithiasis, development of bladder or kidney stones due to alkalinization of urine from urease-catalyzed urea hydrolysis. Adherence of the bacterium to epithelial and catheter surfaces is mediated by 17 different fimbriae, most notably MR/P fimbriae. Repressors of motility are often encoded by these fimbrial operons. Motility is mediated by flagella encoded on a single contiguous 54 kb chromosomal sequence. On agar plates, P. mirabilis undergoes a morphological conversion to a filamentous swarmer cell expressing hundreds of flagella. When swarms from different strains meet, a line of demarcation, a “Dienes line”, develops due to the killing action of each strain’s type VI secretion system. During infection, histological damage is caused by cytotoxins including hemolysin and a variety of proteases, some autotransported. The pathogenesis of infection, including assessment of individual genes or global screens for virulence or fitness factors has been assessed in murine models of ascending UTI or CAUTI using both single-species and polymicrobial models. Global gene expression studies carried out in culture and in the murine model have revealed the unique metabolism of this bacterium. Vaccines, using MR/P fimbria and its adhesin, MrpH, have been shown to be efficacious in the murine model. A comprehensive review of factors associated with urinary tract infection is presented, encompassing both historical perspectives and current advances.

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Section: Virulence Factorsmentioning

confidence: 99%

“…An N-terminal fragment of HpmA, called HpmA265, has been crystallized and its structure solved (Fig. 20) (208). This fragment lacks the C-terminal pore-forming domain, but can still activate full-length HpmA in the absence of HpmB when the proteins are mixed with erythrocytes.…”

Section: Virulence Factorsmentioning

confidence: 99%

Pathogenesis of Proteus mirabilis Infection

2018

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“…In contrast, when wild-type or hpmA mutant P. mirabilis were tested in an IV injection mouse model, the P. mirabilis hpmA mutant had a 6-fold higher LD 50 than wild-type P. mirabilis , suggesting that hemolysin might be important during septic infection (219). A truncated hemolysin crystal structure has been solved, and a CXXC disulfide bond motif contributes to activity and stability of the protein (221). Co-challenge experiments with P. mirabilis hpmA mutant and wild-type P. mirabilis coupled with examination of tissue pathology are needed to further clarify the role of hemolysin in P. mirabilis infection.…”

Section: Trimeric Autotransportersmentioning

confidence: 99%

Proteus mirabilisand Urinary Tract Infections

2015

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Proteus mirabilis is a Gram-negative bacterium which is well-known for its ability to robustly swarm across surfaces in a striking bulls’-eye pattern. Clinically, this organism is most frequently a pathogen of the urinary tract, particularly in patients undergoing long-term catheterization. This review covers P. mirabilis with a focus on urinary tract infections (UTI), including disease models, vaccine development efforts, and clinical perspectives. Flagella-mediated motility, both swimming and swarming, is a central facet of this organism. The regulation of this complex process and its contribution to virulence is discussed, along with the type VI-secretion system-dependent intra-strain competition which occurs during swarming. P. mirabilis uses a diverse set of virulence factors to access and colonize the host urinary tract, including urease and stone formation, fimbriae and other adhesins, iron and zinc acquisition, proteases and toxins, biofilm formation, and regulation of pathogenesis. While significant advances in this field have been made, challenges remain to combatting complicated UTI and deciphering P. mirabilis pathogenesis.

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“…All TpsA proteins harbor a conserved ϳ250-amino-acid N-terminal domain required for secretion called a TPS domain (1,4). Based on existing crystal structures, the TPS domain forms a right-handed ␤-helix with a few extrahelical motifs (5)(6)(7)(8).…”

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confidence: 99%

Structural Determinants of the Interaction between the TpsA and TpsB Proteins in the Haemophilus influenzae HMW1 Two-Partner Secretion System

2015

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The two-partner secretion (TPS) pathway in Gram-negative bacteria consists of a TpsA exoprotein and a cognate TpsB outer membrane pore-forming translocator protein. Previous work has demonstrated that the TpsA protein contains an N-terminal TPS domain that plays an important role in targeting the TpsB protein and is required for secretion. The nontypeable Haemophilus influenzae HMW1 and HMW2 adhesins are homologous proteins that are prototype TpsA proteins and are secreted by the HMW1B and HMW2B TpsB proteins. In the present study, we sought to define the structural determinants of HMW1 interaction with HMW1B during the transport process and while anchored to the bacterial surface. Modeling of HMW1B revealed an N-terminal periplasmic region that contains two polypeptide transport-associated (POTRA) domains and a C-terminal membrane-localized region that forms a pore. Biochemical studies demonstrated that HMW1 engages HMW1B via interaction between the HMW1 TPS domain and the HMW1B periplasmic region, specifically, the predicted POTRA1 and POTRA2 domains. Subsequently, HMW1 is shuttled to the HMW1B pore, facilitated by the N-terminal region, the middle region, and the NPNG motif in the HMW1 TPS domain. Additional analysis revealed that the interaction between HMW1 and HMW1B is highly specific and is dependent upon the POTRA domains and the pore-forming domain of HMW1B. Further studies established that tethering of HMW1 to the surface-exposed region of HMW1B is dependent upon the external loops of HMW1B formed by residues 267 to 283 and residues 324 to 330. These observations may have broad relevance to proteins secreted by the TPS pathway. IMPORTANCESecretion of HMW1 involves a recognition event between the extended form of the HMW1 propiece and the HMW1B POTRA domains. Our results identify specific interactions between the HMW1 propiece and the periplasmic HMW1B POTRA domains. The results also suggest that the process of HMW1 translocation involves at least two discrete steps, including initial interaction between the HMW1 propiece and the HMW1B POTRA domains and then a separate translocation event. We have also discovered that the HMW1B pore itself appears to influence the translocation process. These observations extend our knowledge of the two-partner secretion system and may be broadly relevant to other proteins secreted by the TPS pathway. G ram-negative bacteria have developed a number of pathways for targeting proteins to an extracellular location (1). Among the most common of these pathways is the two-partner secretion (TPS) system. TPS systems typically consist of a large secreted protein called a TpsA protein (encoded by a tpsA gene) and a cognate outer membrane pore-forming translocator protein called a TpsB protein (encoded by a tpsB gene) (2). In addition, some TPS systems include a protein that has glycosyltransferase activity and modifies the TpsA protein (3).TpsA proteins are rich in ␤ structure and are involved in a variety of functions on the bacterial surface or in the extracellular mil...

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Structural and Functional Studies of Truncated Hemolysin A from Proteus mirabilis

Cited by 35 publications

References 43 publications

Pathogenesis of Proteus mirabilis Infection

Pathogenesis of Proteus mirabilis Infection

Proteus mirabilisand Urinary Tract Infections

Structural Determinants of the Interaction between the TpsA and TpsB Proteins in the Haemophilus influenzae HMW1 Two-Partner Secretion System

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