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Title: Structural and Functional Divergence of the Aldolase Fold in Toxoplasma gondii

Parasites of the phylum Apicomplexa are highly successful pathogens of humans and animals worldwide. As obligate intracellular parasites, they have significant energy requirements for invasion and gliding motility that are supplied by various metabolic pathways. Aldolases have emerged as key enzymes involved in these pathways, and all apicomplexans express one or both of fructose 1,6-bisphosphate (F16BP) aldolase and 2-deoxyribose 5-phosphate (dR5P) aldolase (DERA). Intriguingly, Toxoplasma gondii, a highly successful apicomplexan parasite, expresses F16BP aldolase (TgALD1), d5RP aldolase (TgDERA), and a divergent dR5P aldolase-like protein (TgDPA) exclusively in the latent bradyzoite stage. While the importance of TgALD1 in glycolysis is well established and TgDERA is also likely to be involved in parasite metabolism, the detailed function of TgDPA remains elusive. Here, to gain mechanistic insight into the function of different T. gondii aldolases, we first determined the crystal structures of TgALD1 and TgDPA. Structural analysis revealed that both aldolases adopt a TIM barrel fold accessorized with divergent secondary structure elements. Structural comparison of TgALD1 and TgDPA with members of their respective enzyme families revealed that, while the active-site residues are conserved in TgALD1, key catalytic residues are absent in TgDPA. Consistent with this observation, biochemical assays showed that, while TgALD1 wasmore » active on F16BP, TgDPA was inactive on dR5P. In conclusion, intriguingly, both aldolases are competent to bind polymerized actin in vitro. Altogether, structural and biochemical analyses of T. gondii aldolase and aldolase-like proteins reveal diverse functionalization of the classic TIM barrel aldolase fold.« less
 [1] ;  [2] ;  [1] ;  [2] ;  [3] ;  [4] ;  [1]
  1. Univ. of Victoria, BC (Canada)
  2. Northwestern Univ., Chicago, IL (United States). Center for Structural Genomics of Infectious Diseases, Dept. of Biochemistry and Molecular Genetics
  3. Obihiro Univ. of Agriculture and Veterinary Medicine, Obihiro, Hokkaido (Japan). National Research Center for Protozoan Diseases
  4. Northwestern Univ., Chicago, IL (United States). Center for Structural Genomics of Infectious Diseases, Dept. of Biochemistry and Molecular Genetics; BrainMicro LLC, New Haven, CT (United States)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
AC02-06CH11357; MOP82915; HHSN272200700058C; HHSN272201200026C; 085P1000817; 3RO1DAO13141-08S1
Accepted Manuscript
Journal Name:
Journal of Molecular Biology
Additional Journal Information:
Journal Volume: 427; Journal Issue: 4; Journal ID: ISSN 0022-2836
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org:
USDOE; Canadian Institutes for Health Research; National Institutes of Health (NIH); Michigan Economic Development Corporation
Country of Publication:
United States
59 BASIC BIOLOGICAL SCIENCES; Apicomplexa; X-ray crystallography; F16BP aldolase; dR5P aldolase; pseudoaldolase