Structure Dihydrolipoyl transacetylase

the cubic catalytic core structure made of 24 dihydrolipoyl transacetylase subunits.



the dodecahedral catalytic core structure made of 60 dihydrolipoyl transacetylase subunits geobacillus stearothermophilus: 3d electron microscopy map (left) , x-ray diffraction structure (right).

all dihydrolipoyl transacetylases have unique multidomain structure consisting of (from n c): 3 lipoyl domains, interaction domain, , catalytic domain (see domain architecture @ pfam). interestingly domains connected disordered, low complexity linker regions.

depending on species, multiple subunits of dihydrolipoyl transacetylase enzymes can arrange either cubic or dodecahedral shape. these structure form catalytic core of pyruvate dehydrogenase complex not catalyzes reaction transfers acetyl group coa, performs crucial structural role in creating architecture of overall complex.

cube

the cubic core structure, found in species such azotobacter vinelandii, made of 24 subunits total. catalytic domains assembled trimers active site located @ subunit interface. topology of trimer active site identical of chloramphenicol acetyltransferase. 8 of these trimers arranged hollow truncated cube. 2 main substrates, coa , lipoamide (lip(sh)2), found @ 2 opposite entrances of 30 Å long channel runs between subunits , forms catalytic center. coa enters inside of cube, , lipoamide enters outside.

dodecahedron

in many species, including bacteria such geobacillus stearothermophilus , enterococcus faecalis mammals such humans , cows, dodecahedral core structure made of 60 subunits total. subunits arranged in sets of three, similar trimers in cubic core shape, each set making 1 of 20 dodecahedral vertices.