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Literature summary for 3.2.1.68 extracted from

  • Sim, L.; Beeren, S.R.; Findinier, J.; Dauvillee, D.; Ball, S.G.; Henriksen, A.; Palcic, M.M.
    Crystal structure of the Chlamydomonas starch debranching enzyme isoamylase ISA1 reveals insights into the mechanism of branch trimming and complex assembly (2014), J. Biol. Chem., 289, 22991-23003.
    View publication on PubMedView publication on EuropePMC
Search for more literature for 3.2.1.68

Cloned(Commentary)

Cloned (Comment) Organism
the STA7 locus encodes ISA1, recombinant expression of His-tagged subunit ISA1 in Escherichia coli strain BL21(DE3) Chlamydomonas reinhardtii
the STA8 locus encodes ISA2, recombinant expression of HA-tagged ISA2 in strain BafV13 and BafO6 Chlamydomonas reinhardtii

Crystallization (Commentary)

Crystallization (Comment) Organism
purified subunit ISA1 alone and in complex with maltoheptaose, X-ray diffraction structure determination at 2.3 A and 2.4 A, respectively Chlamydomonas reinhardtii
purified subunit ISA1 alone and in complex with maltoheptaose, X-ray diffrcation structure determination at 2.3 A and 2.4 A, respectively. The subunit structure includes highly conserved catalytic (beta/alpha)8 A-domain (aa 184-750), N-terminal beta-sandwich domain (aa 76-183), and C-terminal beta-sandwich domain (aa 751-875) Chlamydomonas reinhardtii

Protein Variants

Protein Variants Comment Organism
additional information functional complementation of sta8 mutant strains BafV13 and BafO6 with ISA2 or ISA2-HA, overview Chlamydomonas reinhardtii

Molecular Weight [Da]

Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
93000
-
 2 * 93000, subunit ISA1, crystal structure analysis and SDS-PAGE Chlamydomonas reinhardtii
180000
-
 subunit ISA1, crystal structure analysis and SDS-PAGE Chlamydomonas reinhardtii

Organism

Organism UniProt Comment Textmining
Chlamydomonas reinhardtii A8IQR3
-
-
Chlamydomonas reinhardtii Q7X8Q2
-
-
Chlamydomonas reinhardtii 330 A8IQR3
-
-
Chlamydomonas reinhardtii 330 Q7X8Q2
-
-

Purification (Commentary)

Purification (Comment) Organism
recombinant His-tagged subunit ISA1 from Escherichia coli strain BL21(DE3) by nickel affinity chromatography Chlamydomonas reinhardtii

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
amylopectin + H2O
-
 Chlamydomonas reinhardtii ?
-
 ?
amylopectin + H2O
-
 Chlamydomonas reinhardtii 330 ?
-
 ?
beta-limit dextrin + H2O
-
 Chlamydomonas reinhardtii ?
-
 ?
beta-limit dextrin + H2O
-
 Chlamydomonas reinhardtii 330 ?
-
 ?
glycogen + H2O
-
 Chlamydomonas reinhardtii ?
-
 ?
glycogen + H2O
-
 Chlamydomonas reinhardtii 330 ?
-
 ?
additional information pullulan is a poor substrate Chlamydomonas reinhardtii ?
-
 ?
additional information pullulan is a poor substrate Chlamydomonas reinhardtii 330 ?
-
 ?
starch + H2O specific hydrolysis of alpha-1,6-glucosidic linkages Chlamydomonas reinhardtii ? detection of aminobenzamide-labeled maltooligosaccharide products, overview ?
starch + H2O specific hydrolysis of alpha-1,6-glucosidic linkages Chlamydomonas reinhardtii 330 ? detection of aminobenzamide-labeled maltooligosaccharide products, overview ?

Subunits

Subunits Comment Organism
homodimer 2 * 93000, subunit ISA1, crystal structure analysis and SDS-PAGE Chlamydomonas reinhardtii

Synonyms

Synonyms Comment Organism
CrISA1
-
 Chlamydomonas reinhardtii
ISA1
-
 Chlamydomonas reinhardtii
ISA2
-
 Chlamydomonas reinhardtii
isoamylase 1
-
 Chlamydomonas reinhardtii
isoamylase 2
-
 Chlamydomonas reinhardtii
starch debranching enzyme
-
 Chlamydomonas reinhardtii

pH Optimum

pH Optimum Minimum pH Optimum Maximum Comment Organism
7
-
 assay at Chlamydomonas reinhardtii

General Information

General Information Comment Organism
evolution subunit ISA1 is a family 13 glycoside hydrolase, which has activity for hydrolyzing alpha-1,6-glucosidic linkages corresponding to branch points of growing amylopectin molecules Chlamydomonas reinhardtii
evolution subunit ISA2 is a family 13 glycoside hydrolase, but its putative catalytic residues are altered, rendering it enzymatically inactive. Despite its inactivity, ISA2 is evolutionarily conserved in plants, and has been suggested to play a role as a regulatory subunit for ISA1 Chlamydomonas reinhardtii
malfunction mutants of the STA8 locus accumulate both phytoglycogen and a reduced amount of high amylose starch Chlamydomonas reinhardtii
malfunction mutation of the STA7 locus leads to a very severe reduction of starch content and its replacement by a water-soluble polysaccharide phytoglycogen Chlamydomonas reinhardtii
additional information subunit ISA2 interacts physically with ISA1, presence of both homomeric ISA1 and heteromeric ISA1-ISA2 complexes in vivo Chlamydomonas reinhardtii
additional information subunit ISA2 interacts physically with ISA1, presence of both homomeric ISA1 and heteromeric ISA1-ISA2 complexes in vivo. Subunit ISA1 enzyme is also partially functional without subunit ISA2 Chlamydomonas reinhardtii
physiological function starch debranching enzymes isoamylase 1 and 2, ISA1 and ISA2, are known to exist in a large complex and are involved in the biosynthesis and crystallization of starch. The function of the complex is to remove misplaced branches of growing amylopectin molecules, which would otherwise prevent the association and crystallization of adjacent linear chains Chlamydomonas reinhardtii
physiological function starch debranching enzymes isoamylase 1 and 2, ISA1 and ISA2, are known to exist in a large complex and are involved in the biosynthesis and crystallization of starch. The function of the complex is to remove misplaced branches of growing amylopectin molecules, which would otherwise prevent the association and crystallization of adjacent linear chains. ISA2 plays a role as a regulatory subunit for ISA1 Chlamydomonas reinhardtii