Characterization of the C-Terminal Propeptide Involved in Bacterial Wall Spanning of Alpha-Amylase from the Psychrophile Alteromonas Haloplanctis
peer reviewed The antarctic psychrophile Alteromonas haloplanctis secretes a Ca2+- and Cl--dependent alpha-amylase. The nucleotide sequence of the amy gene and the amino acid sequences of the gene products indicate that the alpha-amylase precursor is a preproenzyme composed by the signal peptide (24...
Published in: | Journal of Biological Chemistry |
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Main Authors: | , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
American Society for Biochemistry and Molecular Biology
1998
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Subjects: | |
Online Access: | https://orbi.uliege.be/handle/2268/16076 https://orbi.uliege.be/bitstream/2268/16076/1/JBC_1998_Ct.pdf https://doi.org/10.1074/jbc.273.20.12109 |
Summary: | peer reviewed The antarctic psychrophile Alteromonas haloplanctis secretes a Ca2+- and Cl--dependent alpha-amylase. The nucleotide sequence of the amy gene and the amino acid sequences of the gene products indicate that the alpha-amylase precursor is a preproenzyme composed by the signal peptide (24 residues), the mature alpha-amylase (453 residues, 49 kDa), and a long C-terminal propeptide or secretion helper (192 residues, 21 kDa). In cultures of the wild-type strain, the 70-kDa precursor is secreted at the mid-exponential phase and is cleaved by a nonspecific protease into the mature enzyme and the propeptide. The purified C-terminal propeptide displays several features common to beta-pleated transmembrane proteins. It has no intramolecular chaperone function because active alpha-amylase is expressed by Escherichia coli in the absence of the propeptide coding region. In E. coli, the 70-kDa precursor is directed toward the supernatant. When the alpha-amylase coding region is excised from the gene, the secretion helper can still promote its own membrane spanning. It can also accept a foreign passenger, as shown by the extracellular routing of a beta-lactamase-propeptide fusion protein. |
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