Patellamide A and C biosynthesis by a microcin-like pathway in Prochloron didemni, the cyanobacterial symbiont of Lissoclinum patella

^*Department of Medicinal Chemistry, University of Utah, Salt Lake City, UT 84112; ^‡The Institute for Genomic Research, Rockville, MD 20850; and ^§Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA 92093

Edited by Robert Haselkorn, University of Chicago, Chicago, IL, and approved April 7, 2005 (received for review February 18, 2005)

View larger version:
- In this window
- In a new window
- Download as PowerPoint Slide
Fig. 1.
Peptides and symbionts from L. patella. (Upper) Single cell of P. didemni (Right) isolated from the ascidian L. patella (Left) (photograph by Chris Ireland, University of Utah). The green pockets near the surface of L. patella are monocultures of P. didemni. (Lower) Patellamides A and C.
View larger version:
- In this window
- In a new window
- Download as PowerPoint Slide
Fig. 2.
PatE sequence. Italic type, the conserved leader sequence; bold type, the proposed start and stop cyclization sequences; underlined type, product CDSs. Sequences corresponding to patellamide C (Upper) and A (Lower) are aligned for clarity.
View larger version:
- In this window
- In a new window
- Download as PowerPoint Slide
Fig. 3.
The pat gene cluster (A) and GC skew (B). Colored genes represent those that can have a function assigned. White genes are those that have no significant homolog; blue genes contains protease activity. The G+C% skew below is altered where a coding region is present, as is common in many species and suggests that the gene predictions are correct (53). Additionally, the increase of the G+C% in this area suggests that this region may have been transferred into this species by means of horizontal gene transfer.
View larger version:
- In this window
- In a new window
- Download as PowerPoint Slide
Fig. 4.
Proof of function of the pat cluster. (A) Standard from 25 ml of culture broth containing 20 μg of patellamides under SRM conditions observing m/z = 725 (patellamide A daughter ion). (B) Two-liter sample of pCR2.1-pat no. 9 under SRM conditions for m/z = 725. (C) Blind control: SRM using a sample identical to that shown in B except that empty pCR2.1 vector was used. y-axis scales are in units of relative abundance (0-100%).
View larger version:
- In this window
- In a new window
- Download as PowerPoint Slide
Fig. 5.
Proposed pathway to patellamides showing the route to patellamide A. Timing of epimerization of alanine remains unclear; it may take place in tandem with thiazole formation (PatD2-catalyzed), at another biosynthetic step, or nonenzymatically (see Results and Discussion).