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Full-Text Articles in Life Sciences

Regulation Of The Vapbc-1 Toxin-Antitoxin Locus In Nontypeable Haemophilus Influenzae, Susan D. Cline, Sehresh Saleem, Dayle A. Daines Mar 2012

Regulation Of The Vapbc-1 Toxin-Antitoxin Locus In Nontypeable Haemophilus Influenzae, Susan D. Cline, Sehresh Saleem, Dayle A. Daines

Biological Sciences Faculty Publications

Nontypeable Haemophilus influenzae (NTHi) are human-adapted commensal bacteria that can cause a number of chronic mucosal infections, including otitis media and bronchitis. One way for these organisms to survive antibiotic therapy and cause recurrent disease is to stop replicating, as most antimicrobials target essential biosynthetic pathways. Toxin-antitoxin (TA) gene pairs have been shown to facilitate entry into a reversible bacteriostatic state. Characteristically, these operons encode a protein toxin and an antitoxin that associate following translation to form a nontoxic complex, which then binds to and regulates the cognate TA promoter. Under stressful conditions, the labile antitoxin is degraded and the …


Toxin-Antitoxic Loci Vapbc-1 And Vapxd Contribute To Survival And Virulence In Nontypeable Haemophilus Influenzae, Dabin Ren, Anna N. Walker, Dayle A. Daines Jan 2012

Toxin-Antitoxic Loci Vapbc-1 And Vapxd Contribute To Survival And Virulence In Nontypeable Haemophilus Influenzae, Dabin Ren, Anna N. Walker, Dayle A. Daines

Biological Sciences Faculty Publications

Background: Nontypeable Haemophilus influenzae (NTHi) is a significant human pathogen responsible for respiratory tract infections and the most common cause of recurrent otitis media. Type II toxin-antitoxin (TA) systems are genetic elements that code for a stable protein toxin and a labile antitoxin that are thought to be involved in metabolic regulation of bacteria by enabling a switch to a dormant state under stress conditions. The contribution to infection persistence of the NTHi TA loci vapBC-1 and vapXD was examined in this study.

Results: Deletions in vapBC-1, vapXD and vapBC-1 vapXD significantly decreased the survival of NTHi co-cultured with …


Mutation In The Plasmodium Falciparum Crt Protein Determines The Stereospecific Activity Of Antimalarial Cinchona Alkaloids, Carol E. Griffin, Jonathan M. Hoke, Upeka Samarakoon, Junhui Duan, Jianbing Mu, Michael T. Ferdig, David C. Warhurst, Roland A. Cooper Jan 2012

Mutation In The Plasmodium Falciparum Crt Protein Determines The Stereospecific Activity Of Antimalarial Cinchona Alkaloids, Carol E. Griffin, Jonathan M. Hoke, Upeka Samarakoon, Junhui Duan, Jianbing Mu, Michael T. Ferdig, David C. Warhurst, Roland A. Cooper

Biological Sciences Faculty Publications

The Cinchona alkaloids are quinoline aminoalcohols that occur as diastereomer pairs, typified by (-)-quinine and (+)-quinidine. The potency of (+)-isomers is greater than the (-)-isomers in vitro and in vivo against Plasmodium falciparum malaria parasites. They may act by the inhibition of heme crystallization within the parasite digestive vacuole in a manner similar to chloroquine. Earlier studies showed that a K76I mutation in the digestive vacuole-associated protein, PfCRT (P. falciparum chloroquine resistance transporter), reversed the normal potency order of quinine and quinidine toward P. falciparum. To further explore PfCRT-alkaloid interactions in the malaria parasite, we measured the in …