Prescott's Microbiology 8th Edition by Joanne Willey, Linda Sherwood, Christopher J. Woolverton, Lansing Prescott, John Harley, Donald Klein

Exercise 3

Electron cryomicroscopy (cryo-EM) employs a process called single particle reconstruction to generate images of macro-molecular assemblies and their components (e.g., flagella, ribosomes, and protein assemblages). A major challenge in the application of cryo-EM is the level of background "noise" relative to the actual signal emitted by the structure in question. In 2008, a method of image processing was reported that reduces this signal-to-noise ratio problem such that the clarity of a viral protein was comparable to a 3.9 angstrom resolution map obtained from X-ray crystallography. This resolution is sufficient so that most amino acid side chains produced a detectable signal. How do you think the development of a cryomicroscopy technique capable of such high structural resolution will impact biology? Suggest two specific areas in microbiology where this could be especially helpful.

Step 1 of 2

Cryomicroscopy techniques have the ability to detect individual amino acid side chains in a protein and thus provide information on protein structure. The majority of protein structures have been determined by X-ray crystallography.

Nuclear magnetic resonance (NMR) is another less popular method. The problem with X-ray crystallography is obtaining a high quality crystal of the protein in question. Many proteins, particularly membrane proteins or highly unstructured proteins cannot be crystalized. NMR is limited to smaller proteins. Cryomicroscopy gives scientists another tool to determine protein structure that is not amenable to crystallography or NMR.