msra enzyme  (Seca)

Journal:

Article Title: Increased Catalytic Efficiency Following Gene Fusion of Bifunctional Methionine Sulfoxide Reductase Enzymes from Shewanella oneidensis

doi: 10.1021/bi701151t

Figure Lengend Snippet: Tertiary structures (top) and sequences (bottom) of Msr proteins highlighting identical (yellow) and conserved (green) amino acids. Side chains implicated in catalysis or substrate recognition are highlighted (12, 49, 50). Structures correspond to MsrB (left) or MsrA (right). Sequences compare amino acids between MsrB from Neisserium gonorrhoeae and MsrA from E. coli with Shewanella oneidensis MR-1 proteins MsrA (SO2337) and MsrBA (SO2588), as determined using the BLAST algorithm (http://www.ncbi.nlm.nih.gov/sutils/genom_table.cgi). Structures correspond to 2gt3.pdb for MsrA from E. coli or 1l1d.pdb for MsrB from Neisseria gonorrhoeae (12, 51, 52), and were drawn using the program RASMOL (53).

Article Snippet: Methionine sulfoxide reductase enzymes MsrA and MsrB have complementary stereospecificies that respectively reduce the S- and R-stereoisomers of methionine sulfoxide (MetSO), and together function as critical antioxidant enzymes.

Techniques:

Journal:

Article Title: Increased Catalytic Efficiency Following Gene Fusion of Bifunctional Methionine Sulfoxide Reductase Enzymes from Shewanella oneidensis

doi: 10.1021/bi701151t

Figure Lengend Snippet: (Top) SDS-PAGE (14% Tris-glycine) gel showing time-dependent mobility changes of CaMox in the presence of either MsrA or MsrBA. (Bottom) Intact protein ESI-MS spectra of unoxidized CaM (A) and oxidized CaM prior to (B) and following incubation for 12 hours with MsrA (C), MsrB (D), an equimolar mixture of MsrA + MsrB (E), and MsrBA (F). Experimental conditions involved CaM (10 μM) incubated with indicated Msr isoforms (1.0 μM) of either MsrBA, MsrA, or MsrB in 10 mM MOPS (pH 7.5), 50 mM KCl, and 15 mM DTT at 25°C. No MetSO reduction is observed in the absence of added DTT, which acts to reduce the active site of Msr enzymes to permit reduction of MetSO.

Article Snippet: Methionine sulfoxide reductase enzymes MsrA and MsrB have complementary stereospecificies that respectively reduce the S- and R-stereoisomers of methionine sulfoxide (MetSO), and together function as critical antioxidant enzymes.

Techniques: SDS Page, Incubation

Journal:

Article Title: Increased Catalytic Efficiency Following Gene Fusion of Bifunctional Methionine Sulfoxide Reductase Enzymes from Shewanella oneidensis

doi: 10.1021/bi701151t

Figure Lengend Snippet: Steady-state anisotropies for FlAsH-labeled CaMox (1.0 μM) in the presence of MsrBA (◆), MsrA (○) and MsrB (●). Reaction mixture consists of NADPH (400 μM), thioredoxin (50 μM), thioredoxin reductase (2 μM), and indicated isoform of Msr (1.0 μM) in 50 mM HEPES (pH 7.5), 140 mM KCl, and 0.2 mM CaCl2 in a total volume of 2 mL. Initial rates associated with MsrBA-dependent increases in anisotropy are (5.9 ± 1.1) × 10−3/min, (0.53 ± 0.12) × 10−3/min, and (0.19 ± 0.02) × 10−3/min for MsrBA, MsrA and MsrB, respectively. Excitation was at 500 nm and emitted light was measured at 530 nm; slit widths were set at 5 nm. Inset: Electrophoretic mobility on SDS-PAGE of FlAsH-labeled CaM (10 μg) prior to (lane 1) and following oxidation of all nine methionines (lane 2) using a 14% Tris-Glycine gel visualized by fluorescence detection (right) or following Coomassie blue staining (left).

Article Snippet: Methionine sulfoxide reductase enzymes MsrA and MsrB have complementary stereospecificies that respectively reduce the S- and R-stereoisomers of methionine sulfoxide (MetSO), and together function as critical antioxidant enzymes.

Techniques: Labeling, SDS Page, Fluorescence, Staining

Journal:

Article Title: Increased Catalytic Efficiency Following Gene Fusion of Bifunctional Methionine Sulfoxide Reductase Enzymes from Shewanella oneidensis

doi: 10.1021/bi701151t

Figure Lengend Snippet: Catalytic activities of Msr isoforms (0.5 μM) against L-MetSO (A) and CaMox (B) for MsrBA (◆; solid lines), MsrA (○; dashed lines) and MsrB (●; dotted lines). Experimental conditions involved 10 mM Tris-HCl (pH 7.5), NADPH (400 μM), thioredoxin (50 μM), and thioredoxin reductase (2 μM) in a total volume of 0.2 mL at 24 °C. Lines represent fits to the Michaelis-Menten rate equation (see Table 1).

Article Snippet: Methionine sulfoxide reductase enzymes MsrA and MsrB have complementary stereospecificies that respectively reduce the S- and R-stereoisomers of methionine sulfoxide (MetSO), and together function as critical antioxidant enzymes.

Techniques:

Journal:

Article Title: Increased Catalytic Efficiency Following Gene Fusion of Bifunctional Methionine Sulfoxide Reductase Enzymes from Shewanella oneidensis

doi: 10.1021/bi701151t

Figure Lengend Snippet: Catalytic Rates of MetSO Repair by Msr Enzymes

Article Snippet: Methionine sulfoxide reductase enzymes MsrA and MsrB have complementary stereospecificies that respectively reduce the S- and R-stereoisomers of methionine sulfoxide (MetSO), and together function as critical antioxidant enzymes.

Techniques:

Journal:

Article Title: Increased Catalytic Efficiency Following Gene Fusion of Bifunctional Methionine Sulfoxide Reductase Enzymes from Shewanella oneidensis

doi: 10.1021/bi701151t

Figure Lengend Snippet: Depiction of proposed role of MsrBA fusion protein (gray connected circles denoted A and B) in binding and stabilizing unfolded state of oxidized CaM (white cylinders)(step 1), permitting reduction of all nine MetSO (yellow) to their native Met structure through the coordinate binding of both active sites A and B in MsrBA (top) at multiple MetSO sites (step 2), where diffusional steps are minimized due to the role of the complemetary protein domain in anchoring MsrBA to the oxidized protein. Underlying thecapacity of MsrBA to fully repair CaMox is an ability to stabilize the oxidized and partially unfolded CaM to promote recognition of exposed MetSO by the Msr enzymes (Figure 4). The ability to maintain the MetSO within protein substrates in an accessible partially unfolded state results in an increased catalytic rates of repair (Figure 5). Following MetSO reduction, MsrBA dissociates, releasing the fully repaired protein (step 3). In contrast, while binding of MsrA (bottom) or MsrB (not depicted) to fully oxidized CaM (step 4) readily occurs, neither MsrA or MsrB alone can fully repair all S- or R-MetSO in CaMox under these experimental conditions, where there is substantial protein refolding at 25 °C (step 5) that competes with the ability of the individual Msr enzymes to recognize and bind MetSO in CaMox (step 5) (5, 6, 25, 32). Following protein refolding, there is no additional reduction of MetSO (step 6 is blocked), resulting in the retention of MetSO as occurs during biological aging (2).

Article Snippet: Methionine sulfoxide reductase enzymes MsrA and MsrB have complementary stereospecificies that respectively reduce the S- and R-stereoisomers of methionine sulfoxide (MetSO), and together function as critical antioxidant enzymes.

Techniques: Binding Assay