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Abstract Bacterial peptidoglycan (PG) synthesis requires strict spatiotemporal organization to reproduce specific cell shapes. In ovoid‐shapedStreptococcus pneumoniae(Spn), septal and peripheral (elongation) PG synthesis occur simultaneously at midcell. To uncover the organization of proteins and activities that carry out these two modes of PG synthesis, we examinedSpncells vertically oriented onto their poles to image the division plane at the high lateral resolution of 3D‐SIM (structured‐illumination microscopy). Labeling with fluorescent D‐amino acids (FDAA) showed that areas of new transpeptidase (TP) activity catalyzed by penicillin‐binding proteins (PBPs) separate into a pair of concentric rings early in division, representing peripheral PG (pPG) synthesis (outer ring) and the leading‐edge (inner ring) of septal PG (sPG) synthesis. Fluorescently tagged PBP2x or FtsZ locate primarily to the inner FDAA‐marked ring, whereas PBP2b and FtsX remain in the outer ring, suggesting roles in sPG or pPG synthesis, respectively. Pulses of FDAA labeling revealed an arrangement of separate regularly spaced “nodes” of TP activity around the division site of predivisional cells. Tagged PBP2x, PBP2b, and FtsX proteins also exhibited nodal patterns with spacing comparable to that of FDAA labeling. Together, these results reveal new aspects of spatially ordered PG synthesis in ovococcal bacteria during cell division.
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Stereodivergent Attached‐Ring Synthesis via Non‐Covalent Interactions: A Short Formal Synthesis of Merrilactone A
Abstract A strategy to control the diastereoselectivity of bond formation at a prochiral attached‐ring bridgehead is reported. An unusual stereodivergent Michael reaction relies on basic vs. Lewis acidic conditions and non‐covalent interactions to controlre‐ vs.si‐ facial selectivity en route to fully substituted attached‐rings. This divergency reflects differential engagement of one rotational isomer of the attached‐ring system. The successful synthesis of anerythrosubtarget diastereomer ultimately leads to a short formal synthesis of merrilactone A.
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- PAR ID:
- 10447950
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 61
- Issue:
- 3
- ISSN:
- 1433-7851
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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