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Lateral Gene Transfer: Using Bioinformatics in Allied Health Microbiology. Ruth Wrightsman Flathead Valley Community College Kalispell, MT Cynthia Brame Centenary College Shreveport, LA. Q&A.
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Lateral Gene Transfer: Using Bioinformatics in Allied Health Microbiology Ruth Wrightsman Flathead Valley Community College Kalispell, MT Cynthia Brame Centenary College Shreveport, LA
Q&A E. coli is found naturally in the human large intestine, and there it is beneficial. However, the strain designated E. coli O157:H7 produces Shiga toxin. How did E. coli acquire this gene from Shigella? From Tortora et al. 10th ed.
The Challenge: Students have problems understanding lateral gene transfer • Assume that all changes are “mutations” • Have trouble understanding “how do we know this?”
Not the first time this problem has been noted………….. • ASM/JGI Bioinformatics Institute 2010 • Presentation: E. coli O157:H7Where Did the Toxin Gene Come From? • Hypothesis testing: • Mutation vs. Gene Transfer
Solution: A bioinformatics approach to study lateral gene transfer Learning Goals: • Learn to use and interpret results from IMG genome comparison • Identify genes associated with pathogenicity • Identify genes associated with lateral gene transfer • Use Pfam to identify protein function
Step 1: Set up the Genome Comparison • Use IMG – Integrated Microbial Genomes • http://img.jgi.doe.gov/cgi-bin/w/main.cgi • Go to “Find Genes” • Choose Phylogenetic Profiler • Choose Single Genes
IMG – Phylogenetic Profiler http://img.jgi.doe.gov/cgi-bin/w/main.cgi
Phylogenetic Comparison • Look for genes that ARE found in: • E. coli O157:H7 EDL 933 (EHEC) • Shigelladysenteriae SD197 • And genes that ARE NOT found in • E. coli DH 1 • Note to self……the strains chosen DO matter!
The Results……….. 93 genes is a reasonable number to examine.
Step 2. Choose some genes to examine. • Students may need some background on pathogenicity mechanisms • References to textbook or CDC reports • May also need some reminders about how gene transfer may occur • References for genetic mechanisms
Step 3: Choose an interesting gene • See where gene is located • Examine environment around gene • See if Pfam has information on protein
Step 4: Extend this process….. • Examine lateral gene transfer in other E. coli strains • Use MUSCLE to align and compare protein sequences • Overlay with solved structure • (Get a pretty picture of the molecule!) • Examine lateral gene transfer in other pathogens • Diphtheria • Cholera