Metaproteomics-guided selection of targeted enzymes for bioprospecting of mixed microbial communities.

Background: Hitherto, the main goal of metaproteomic analyses has been to characterize the functional role of particular microorganisms in the microbial ecology of various microbial communities. Recently, it has been suggested that metaproteomics could be used for bioprospecting microbial communities to query for the most active enzymes to improve the selection process of industrially relevant enzymes. In the present study, to reduce the complexity of metaproteomic samples for targeted bioprospecting of novel enzymes, a microbial community capable of producing cellulases was maintained on a chemically defined medium in an enzyme suppressed metabolic steady state.

Assessment of sample preparation methods for metaproteomics of extracellular proteins.

Enzyme discovery in individual strains of microorganisms is compromised by the limitations of pure culturing. In principle, metaproteomics allows for fractionation and study of different parts of the protein complement but has hitherto mainly been used to identify intracellular proteins. However, the extracellular environment is also expected to comprise a wealth of information regarding important proteins.

Differential conformational modulations of MreB folding upon interactions with GroEL/ES and TRiC chaperonin components.

Here, we study and compare the mechanisms of action of the GroEL/GroES and the TRiC chaperonin systems on MreB client protein variants extracted from E. coli. MreB is a homologue to actin in prokaryotes.

Transient conformational remodeling of folding proteins by GroES-individually and in concert with GroEL.

The commonly accepted dogma of the bacterial GroE chaperonin system entails protein folding mediated by cycles of several ATP-dependent sequential steps where GroEL interacts with the folding client protein. In contrast, we herein report GroES-mediated dynamic remodeling (expansion and compression) of two different protein substrates during folding: the endogenous substrate MreB and carbonic anhydrase (HCAII), a well-characterized protein folding model. GroES was also found to influence GroEL binding induced unfolding and compression of the client protein underlining the synergistic activity of both chaperonins, even in the absence of ATP.

Conformational effects on the circular dichroism of Human Carbonic Anhydrase II: a multilevel computational study.

Circular Dichroism (CD) spectroscopy is a powerful method for investigating conformational changes in proteins and therefore has numerous applications in structural and molecular biology. Here a computational investigation of the CD spectrum of the Human Carbonic Anhydrase II (HCAII), with main focus on the near-UV CD spectra of the wild-type enzyme and it seven tryptophan mutant forms, is presented and compared to experimental studies. Multilevel computational methods (Molecular Dynamics, Semiempirical Quantum Mechanics, Time-Dependent Density Functional Theory) were applied in order to gain insight into the mechanisms of interaction between the aromatic chromophores within the protein environment and understand how the conformational flexibility of the protein influences these mechanisms.