Crystal structure of the receptor binding domain of the botulinum C-D mosaic neurotoxin reveals potential roles of lysines 1118 and 1136 in membrane interactions

Journal Article · Fri Jan 07 00:00:00 EST 2011 · Biochemical and Biophysical Research Communications, 404(1):407-412

DOI:https://doi.org/10.1016/j.bbrc.2010.11.134· OSTI ID:1001455

Zhang, Yanfeng; Buchko, Garry W; Qin, Ling; Robinson, Howard; Varnum, Susan M

The botulinum neurotoxins (BoNTs) produced by different strains of the bacterium Clostridium botulinum are responsible for the disease botulism and include a group of immunologically distinct serotypes (A, B, E, and F) that are considered to be the most lethal natural proteins known for humans. Two BoNT serotypes, C and D, while rarely associated with human infection, are responsible for deadly botulism outbreaks afflicting animals. Also associated with animal infections is the BoNT C-D mosaic protein (BoNT/CD), a BoNT subtype that is essentially a hybrid of the BoNT/C (~two-thirds) and BoNT/D (~one-third) serotypes. While the amino acid sequence of the heavy chain receptor binding (HCR) domain of BoNT/CD (BoNT/CD-HCR) is very similar to the corresponding amino acid sequence of BoNT/D, BoNT/CD-HCR binds synaptosome membranes better than BoNT/D-HCR. To obtain structural insights for the different membrane binding properties, the crystal structure of BoNT/CD-HCR (S867-E1280) was determined at 1.56 Å resolution and compared to previously reported structures for BoNT/D-HCR. Overall, the BoNT/CD-HCR structure is similar to the two sub-domain organization observed for other BoNT HCRs: an N-terminal jellyroll barrel motif and a C-terminal β-trefoil fold. Comparison of the structure of BoNT/CD-HCR with BoNT/D-HCR indicates that K1118 has a similar structural role as the equivalent residue, E1114, in BoNT/D-HCR, while K1136 has a structurally different role than the equivalent residue, G1132, in BoNT/D-HCR. Lysine-1118 forms a salt bridge with E1247 and may enhance membrane interactions by stabilizing the putative membrane binding loop (K1240-N1248). Lysine-1136 is observed on the surface of the protein. A sulfate ion bound to K1136 may mimic a natural interaction with the negatively changed phospholipid membrane surface. Liposome-binding experiments demonstrate that BoNT/CD-HCR binds phosphatidylethanolamine liposomes more tightly than BoNT/D-HCR

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1001455
• Report Number(s): PNNL-SA-76463; BBRCA9; 41092; 34699; 400412000; TRN: US201102%%162
• Journal Information: Biochemical and Biophysical Research Communications, 404(1):407-412, Vol. 404, Issue 1; ISSN 0006-291X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AMINO ACID SEQUENCE
ANIMALS
CHAINS
CLOSTRIDIUM BOTULINUM
CRYSTAL STRUCTURE
DISEASES
LIPOSOMES
MEMBRANES
PHOSPHOLIPIDS
PROTEINS
RESOLUTION
STRAINS
SULFATES
botulinum neurotoxin
C-D mosaic
botulism
phosphatidylethanolamine
membrane recognition
SSGCID
Environmental Molecular Sciences Laboratory