University of Queensland

About: University of Queensland is a education organization based out in Brisbane, Queensland, Australia. It is known for research contribution in the topics: Population & Poison control. The organization has 51138 authors who have published 155721 publications receiving 5717659 citations. The organization is also known as: UQ & The University of Queensland.

Anaerobic oxidation of methane coupled to nitrate reduction in a novel archaeal lineage

Abstract: An anaerobic methanotroph (ANME-2d) can perform nitrate-driven anaerobic oxidation of methane through reverse methanogenesis, using nitrate as the terminal electron acceptor, and nitrite produced by ANME-2d is reduced to dinitrogen gas through a syntrophic relationship with an anaerobic ammonium-oxidizing bacterium. Microbes capable of the anaerobic oxidation of methane (AOM) are important for controlling the flux of methane from anoxic marine sediments. Recent work has demonstrated AOM coupled to sulphate reduction in a consortium of ANME (anaerobic methanotrophic archaea) and sulphate-reducing bacteria, and coupled to nitrite reduction in consortia enriched with the bacterium Candidatus Methylomirabilis oxyfera and the novel ANME-2d lineage. Here Gene Tyson and colleagues show that a novel ANME-2d archaeon, which they name Candidatus Methanoperedens nitroreducens, is able to performing nitrate-driven AOM without a partner organism via reverse methanogenesis with nitrate as the terminal electron acceptor, using genes for nitrate reduction that have been laterally transferred from a bacterial donor. The authors speculate that ANME- 2d or Methanoperedenaceae lineage may have a pivotal role in linking the global carbon and nitrogen cycles in anoxic environments. Anaerobic oxidation of methane (AOM) is critical for controlling the flux of methane from anoxic environments. AOM coupled to iron1, manganese1 and sulphate2 reduction have been demonstrated in consortia containing anaerobic methanotrophic (ANME) archaea. More recently it has been shown that the bacterium Candidatus ‘Methylomirabilis oxyfera’ can couple AOM to nitrite reduction through an intra-aerobic methane oxidation pathway3. Bioreactors capable of AOM coupled to denitrification have resulted in the enrichment of ‘M. oxyfera’ and a novel ANME lineage, ANME-2d4,5. However, as ‘M. oxyfera’ can independently couple AOM to denitrification, the role of ANME-2d in the process is unresolved. Here, a bioreactor fed with nitrate, ammonium and methane was dominated by a single ANME-2d population performing nitrate-driven AOM. Metagenomic, single-cell genomic and metatranscriptomic analyses combined with bioreactor performance and 13C- and 15N-labelling experiments show that ANME-2d is capable of independent AOM through reverse methanogenesis using nitrate as the terminal electron acceptor. Comparative analyses reveal that the genes for nitrate reduction were transferred laterally from a bacterial donor, suggesting selection for this novel process within ANME-2d. Nitrite produced by ANME-2d is reduced to dinitrogen gas through a syntrophic relationship with an anaerobic ammonium-oxidizing bacterium, effectively outcompeting ‘M. oxyfera’ in the system. We propose the name Candidatus ‘Methanoperedens nitroreducens’ for the ANME-2d population and the family Candidatus ‘Methanoperedenaceae’ for the ANME-2d lineage. We predict that ‘M. nitroreducens’ and other members of the ‘Methanoperedenaceae’ have an important role in linking the global carbon and nitrogen cycles in anoxic environments.

In situ neutralization in Boc-chemistry solid phase peptide synthesis. Rapid, high yield assembly of difficult sequences.

Abstract: Simple, effective protocols have been developed for manual and machine-assisted Boc-chemistry solid phase peptide synthesis on polystyrene resins. These use in situ neutralization [i.e. neutralization simultaneous with coupling], high concentrations (> 0.2 M) of Boc-amino acid-OBt esters plus base for rapid coupling, 100% TFA for rapid Boc group removal, and a single short (30 s) DMF flow wash between deprotection/coupling and between coupling/deprotection. Single 10 min coupling times were used throughout. Overall cycle times were 15 min for manual and 19 min for machine-assisted synthesis (75 residues per day). No racemization was detected in the base-catalyzed coupling step. Several side reactions were studied, and eliminated. These included: pyrrolidonecarboxylic acid formation from Gln in hot TFA-DMF; chain-termination by reaction with excess HBTU; and, chain termination by acetylation (from HOAc in commercial Boc-amino acids). The in situ neutralization protocols gave a significant increase in the efficiency of chain assembly, especially for “difficult” sequences arising from sequence-dependent peptide chain aggregation in standard (neutralization prior to coupling) Boc-chemistry SPPS protocols or in Fmoc-chemistry SPPS. Reported syntheses include HIV-1 protease(1–50,Cys.amide), HIV-1 protease(53–99), and the full length HIV-1 protease(1–99).