6: More Bacterial Cell Wall Stuff

I've just had a drink or two, and I'm rushing, but we'll see how this goes:

Control of Cell Shape in Bacteria: Helical, Actin-like Filaments in Bacillus subtilis
Jones,et al. Cell 2001

Overview
So, in eukaryotes, cell shape is most often dictated by the cytoskeleton (mostly actin filaments). But what about in bacteria? This paper analyzed B. subtilis mutants in MreB and Mrel, which happen to have a spherical cell phenotype.

Results
First they demonstrated that MreB was essential for B subtilis (even though it's not for E. coli), and phenotypic analysis of cells depleted in MreB showed they had an abnormal, rounded and wide morphology compared to wild-type rods. Mrel mutants, however, had abnormal curvature, but were viable, and the authors hypothesized that this protein is involved in coordinating the FtsZ ring involved in cytokinesis after mitosis.

So, they tried looking at GFP-MreB under the microscope, but it was dispersed throughout the cell. Then they tried using a monoclonal antibody for c-Myc-MreB, and found that it formed helical structures (they have a hard time showing this with 2D microscope images). Using quantitative immunoblotting, they estimated ~8,000 molecules/cell. They used the same technique to visualize Mrel double helices in vivo. Finally, they made some mutations in MreB, and showed that these altered cell morphology. After analyzing some sequences, they saw that MreB/MreI were absent from coccoid bacteria, and proposed a model where these proteins fulfill the role of actin in bacteria (sequence alignment shows few gaps between the proteins) and control cell axes through assembly in an ATP-dependent manner.

Control of Cell Morphogenesis in Bacteria: Two Distinct Ways to Make a Rod-Shaped Cell
Daniel, et al. Cell 2003

Summary
In this paper, they used a fluorescently-labelled vancomycin probe to explore peptidoglycan structure, assembly, and its effect on cell shape.

They found nascent peptidoglycan assembly was directed in a helical manner dependent on Mrel, which is a homolog of MreB. Without Mrel around, they hypothesized that B. subtilis switches to a polar mode of growth (basically, directed by cell division).

Distinct penicillin binding proteins involved in the division, elongation, and shape of Escherichia coli K12
Spratt 1975 PNAS

Summary
This paper is pretty old, and couldn't get to much specific detail, but was able to use fluorography of displaced radiolabelled antibiotics to identify penicillin binding proteins with roles in cell shape and division. The following is pretty ridiculous:
"The binding proteins were detected by fluorography (14) on Kodak RPRoyal x-ray film for 48 days at -70C."
Wow. If it took me 48 days straight to get data, I think I'd give up on science.