Found in muddy soils near hot springs, Heliobacterium modesticaldum is the simplest bacterium known to be able to drive photosynthesis. Its photosynthesis reaction centers are thought to resemble the earliest common ancestor of all photosynthesis complexes, which evolved around three billion years ago. Now, for the first time, a team led by researchers from Arizona State University has obtained a near-atomic resolution (2.2 Å) structure of the membrane protein at the heart of H. modesticaldum’s photosynthetic reaction center using X-ray crystallography data collected at ALS Beamline 8.2.1. The structure gives researchers a new perspective on the early evolution of photosynthesis. Read more in this ALS Science Brief.
CRISPR Target Recognition Mechanism Illuminated Using Data From ALS
Using diffraction data obtained at Berkeley Lab’s Advanced Light Source (ALS) and at the Stanford Synchrotron Radiation Lightsource (SSRL), researchers in Biosciences’ Molecular Biophysics & Integrated Bioimaging (MBIB) division and at UC Berkeley have discovered how CRISPR-associated (Cas) proteins are able to recognize their target locations with such great specificity. X-ray crystallography was used to solve the structures of Cas1 and Cas2—responsible for DNA-snippet capture and integration—as they were bound to synthesized DNA strands designed to mimic different stages of the process. The resulting structures show how the system works in its native context as part of a bacterial immune system, and also inform the development of the CRISPR-Cas system as a general-purpose molecular recording device. Jun-Jie Liu, a joint postdoc in the labs of Jennifer Doudna and Eva Nogales, and Addison Wright, a graduate student in Doudna’s lab, were co-first authors on the paper, published in the journal Science. Read more in this ALS Science Highlight.
NIH Awards $6.5 Million for Augmenting Structural Biology Research Experience
The National Institutes of Health (NIH) has awarded $6.5 million to Berkeley Lab to integrate existing synchrotron structural biology resources to better serve researchers. The grant will establish a center based at the Lab’s Advanced Light Source (ALS) called ALS-ENABLE that will guide users through the most appropriate routes for answering their specific biological questions.
Carolyn Larabell to Receive Shirley Award at ALS User Meeting
Carolyn Larabell, a professor at the UC San Francisco School of Medicine and a faculty scientist in the Molecular Biophysics and Integrated Bioimaging (MBIB) Division at Berkeley Lab, has been selected by the Advanced Light Source (ALS) Users’ Executive Committee to receive the 2017 David A. Shirley Award for Outstanding Scientific Achievement. Larabell directs the National Center for X-Ray Tomography (NCXT) centered around ALS Beamline 2.1, the world’s first soft x-ray microscope for biological imaging, and she led the group responsible for its commissioning, design, and construction. Soft x-ray tomography makes it possible to image intact biological cells in 3-D without structure-damaging preparation such as chemically fixing, dehydrating, and staining the specimens. On October 3, Larabell will give her award talk, entitled “The Expanding Universe of Cell Biology at the NCXT,” during the ALS User Meeting at Berkeley Lab. Read more in ALS News & Updates.
X-ray Footprinting Reveals Secrets of ‘Metal-Breathing’ Bacterium
A team of Berkeley Lab researchers conducted X-ray footprinting mass spectrometry (XFMS) experiments at the Lab’s Advanced Light Source (ALS) to pinpoint how a protein of the bacterium Shewanella oneidensis transfers electrons to a metal oxide substrate. The research was led by Caroline Ajo-Franklin, whose lab is part of the Molecular Foundry and who holds a secondary appointment in the Molecular Biophysics and Integrated Bioimaging (MBIB) division, in collaboration with Corie Ralston, also of MBIB. Tatsuya Fukushima, a former postdoc in Ajo-Franklin’s lab, and Sayan Gupta, a member of Ralston’s lab, were co-first authors on the paper published in the Journal of the American Chemical Society. The study, which identified an unexpectedly small and weak binding site, also benefitted from expertise and tools contributed by Joint BioEnergy Institute (JBEI) and Biological Systems and Engineering (BSE) researchers Christopher Petzold and Leanne Jade Chan. Read more at the Berkeley Lab News Center.
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