Current News
Microbiology of arsenic-contaminated agricultural soils in the Mekong River and Red River deltas
Max Häggblom (Department of Biochemistry ad Microbiology) and John Reinfelder (Department of Environmental Sciences) visited Vietnam to initiate collaborative research on microbial arsenic metabolism in rice paddy soils with investigators at Can Tho University, College of Agriculture and Hanoi University of Science and Technology, School of Biotechnology and Food Technology.
Arsenic (As) contamination of groundwater is of serious concern in many regions of Southeast Asia, including Vietnam, and is linked to As contamination of paddy soils, which threatens the health of populations relying on rice as a staple crop. Rice consumption is a key pathway for the dietary intake of both essential trace elements and toxicants, including As which is harmful to human health. Although generally present in the environment at low levels, As is actively metabolized by microorganisms, a process that has a strong impact on its mobility and bioavailability. Microbially mediated transformations modulate the toxicity of As and change its mobility and bioavailability, which in turn may affect its translocation and accumulation in plants. Hence, microbial transformations of As can have a direct effect on the nutritional quality of various crops, especially rice. In pilot experiments we aim to cultivate and isolate As-respiring bacteria from agricultural soils in the Mekong and Red River watersheds to obtain site-specific reference strains for physiological characterization and for use in molecular monitoring of community dynamics and activity. With our collaborators we will design a combination of greenhouse experiments and field site analyses comparing water management and rice cultivation methods to demonstrate the activity of As-reducing microbes under in situ conditions and determine how their abundance and activity are affected by changes in the redox environment and differences in site water and soil chemistry.
The Kulczyk Lab Determines a Cryo-EM Structure of the Bacterial Toxin and Ribosomal P-stalk Complex
February 2023
Kulczyk's laboratory, in collaboration with Nilgun Tumer's laboratory, determined a cryo-EM structure of Shiga toxin 2a (Stx2a) in complex with the native ribosomal P-stalk. Stx2a is the virulence factor of Shigella dysenteriae and enterohemorrhagic Escherichia coli, and it is homologous to the ricin toxin. The catalytic A1 subunit of Stx2a interacts with the ribosomal P-stalk for loading onto the ribosome and depurination of the sarcin-ricin loop, whichhalts protein synthesis. The cryo-EM structure, recently published in the Journal of Biological Chemistry, provides the important insight into the intrinsic dynamics of the Stx2a-P-stalk interaction, and identifies residues involved in binding. The structure will be critical for the design of selective small molecule inhibitors for the treatment of bacterial infections.
The Kulczyk Lab Publishes in Nature Communications
January 24, 2023
Arek Kulczyk's laboratory, in collaboration with Peter Yurchenco's laboratory, determined a cryo-EM structure of the laminin polymer node, the basic repeating unit of the laminin lattice. Laminin polymerization is the major step in the assembly of basement membranes, an integral part of the extracellular matrix. Failures in laminin polymerization cause multiple human disorders, including Pierson syndrome and LAMA2 muscular dystrophy. In addition, disruption of laminin polymer impedes cancer metastases. The 3.7 Å cryo-EM structure of the trimeric laminin polymer node consisting of a1, b1 and g1 subunits has been recently published in Nature Communication. The structure reveals fundamental molecular mechanisms of calcium-dependent formation of laminin lattice, and provides detailed insight into polymerization defects manifesting in human disease. The structure offers to facilitate rational drug design aiming in the treatment of laminin deficiencies, and can foster development of biomimetic basement membranes for tissue implants.
