4L28

Crystal structure of delta516-525 human cystathionine beta-synthase D444N mutant containing C-terminal 6xHis tag

Summary for 4L28

• Entry DOI: 10.2210/pdb4l28/pdb
• Related: 1JBQ 4L0D 4L27 4L3V
• Descriptor: Cystathionine beta-synthase, PYRIDOXAL-5'-PHOSPHATE, PROTOPORPHYRIN IX CONTAINING FE (3 entities in total)
• Functional Keywords: cbs domain, homocyteine, cysteine biosynthesis, heme, pyridoxal 5'-phosphate, s-adenosylmethionine, transsulfuration pathway, lyase
• Biological source: Homo sapiens (human)
• Cellular location: Cytoplasm: P35520
• Total number of polymer chains: 4
• Total formula weight: 249871.97

Authors

Ereno, J.,Majtan, T.,Oyenarte, I.,Kraus, J.P.,Martinez, L.A. (deposition date: 2013-06-04, release date: 2013-09-18, Last modification date: 2013-10-16)

Primary citation

Ereno-Orbea, J.,Majtan, T.,Oyenarte, I.,Kraus, J.P.,Martinez-Cruz, L.A.
Structural basis of regulation and oligomerization of human cystathionine beta-synthase, the central enzyme of transsulfuration.
Proc.Natl.Acad.Sci.USA, 110:E3790-E3799, 2013

PubMed Abstract: Cystathionine β-synthase (CBS) controls the flux of sulfur from methionine to cysteine, a precursor of glutathione, taurine, and H2S. CBS condenses serine and homocysteine to cystathionine with the help of three cofactors, heme, pyridoxal-5'-phosphate, and S-adenosyl-l-methionine. Inherited deficiency of CBS activity causes homocystinuria, the most frequent disorder of sulfur metabolism. We present the structure of the human enzyme, discuss the unique arrangement of the CBS domains in the C-terminal region, and propose how they interact with the catalytic core of the complementary subunit to regulate access to the catalytic site. This arrangement clearly contrasts with other proteins containing the CBS domain including the recent Drosophila melanogaster CBS structure. The absence of large conformational changes and the crystal structure of the partially activated pathogenic D444N mutant suggest that the rotation of CBS motifs and relaxation of loops delineating the entrance to the catalytic site represent the most likely molecular mechanism of CBS activation by S-adenosyl-l-methionine. Moreover, our data suggest how tetramers, the native quaternary structure of the mammalian CBS enzymes, are formed. Because of its central role in transsulfuration, redox status, and H2S biogenesis, CBS represents a very attractive therapeutic target. The availability of the structure will help us understand the pathogenicity of the numerous missense mutations causing inherited homocystinuria and will allow the rational design of compounds modulating CBS activity.

PubMed: 24043838
DOI: 10.1073/pnas.1313683110

Experimental method

X-RAY DIFFRACTION (2.626 Å)