Identification and Biochemical Characterization of Sco3487 from Streptomyces coelicolor A3(2), an Exo- and Endo-Type -Agarase-Producing Neoagarobiose
Streptomyces coelicolor can degrade agar, the main cell wall component of red macroalgae, for growth. To constitute a crucial carbon source for bacterial growth, the alternating α-(1,3) and β-(1,4) linkages between the 3,6-anhydro-l-galactoses and d-galactoses of agar must be hydrolyzed by α/β-agara...
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Veröffentlicht in: | Journal of bacteriology 2012-01, Vol.194 (1), p.142-149 |
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Zusammenfassung: | Streptomyces coelicolor can degrade agar, the main cell wall component of red macroalgae, for growth. To constitute a crucial carbon source for bacterial growth, the alternating α-(1,3) and β-(1,4) linkages between the 3,6-anhydro-l-galactoses and d-galactoses of agar must be hydrolyzed by α/β-agarases. In S. coelicolor, DagA was confirmed to be an endo-type β-agarase that degrades agar into neoagarotetraose and neoagarohexaose. Genomic sequencing data of S. coelicolor revealed that Sco3487, annotated as a putative hydrolase, has high similarity to the glycoside hydrolase (GH) GH50 β-agarases. Sco3487 encodes a primary translation product (88.5 kDa) of 798 amino acids, including a 45-amino-acid signal peptide. The sco3487 gene was cloned and expressed under the control of the ermE promoter in Streptomyces lividans TK24. β-Agarase activity was detected in transformant culture broth using the artificial chromogenic substrate p-nitrophenyl-β-d-galactopyranoside. Mature Sco3487 (83.9 kDa) was purified 52-fold with a yield of 66% from the culture broth. The optimum pH and temperature for Sco3487 activity were 7.0 and 40...C, respectively. The K... and V... for agarose were 4.87 mg/ml (4 x 10... M) and 10.75 U/mg, respectively. Sco3487 did not require metal ions for its activity, but severe inhibition by Mn... and Cu... was observed. Thin-layer chromatography analysis, matrix-assisted laser desorption ionization-time of flight mass spectrometry, and Fourier transform-nuclear magnetic resonance spectrometry of the Sco3487 hydrolysis products revealed that Sco3487 is both an exo- and endo-type β-agarase that degrades agarose, neoagarotetraose, and neoagarohexaose into neoagarobiose. (ProQuest: ... denotes formulae/symbols omitted.) |
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ISSN: | 0021-9193 1098-5530 |
DOI: | 10.1128/JB.05978-11 |