Field of Science

Searching for motifs

Well, I don't know why my first attempt at running a Gibbs motif search with the Gallibacterium genome returned errors. The errors it described were ones I hadn't made (as far as I could tell), so I resubmitted the runs and they were fine.

But the grid-computer system was slow to get around to my runs (probably those physicists and meteorologists hogging the system), so I poked around and rediscovered that the Gibbs motif searcher program now also runs on Macs. Luckily one of the post-docs had just come back from a two-week course that required intensive use of Unix, so she was able to dive in and sort out the permissions etc. for me. So now I can run the Gibbs searches on my newish MacBook Pro and on our other fast Mac. And I can also still run them on the grid system too.

Results: I can't find anything (i.e. Gibbs can't find anything) in the Gallibacterium genome that looks anything like a typical Pasteurellacean uptake sequence. I've done simple searches where I just asked it to look for an 8-mer motif, and searches wherre I gave it 'segmentation-mask' prior files telling it the spacing typical of a H. influenzae or A. pleuropneumoniae USS, but it still didn't find anything. Most of the time it can't find anything it even considers to be a motif at all. This may be because the USS motifs are too sparse for it to pick them up, or because Gallibacterium really doesn't have a USS at all.

But I'm trying one more thing - giving it a prior file that specifies not just the spacing but the actual position weight matrix to expect. If this doesn't find anything we may need to do some uptake-specificity experiments.

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