Recent work in computational genomics has shown that a functional association 
between two genes can be derived from the existence of a fusion of the two as 
one continuous sequence in another genome. For each of 30 completely sequenced 
microbial genomes, we established all such fusion links among its genes and 
determined the distribution of links within and among 15 broad functional 
categories. We found that 72% of all fusion links related genes of the same 
functional category. A comparison of the distribution of links to simulations on 
the basis of a random model further confirmed the significance of intracategory 
fusion links. Where a gene of annotated function is linked to an unclassified 
gene, the fusion link suggests that the two genes belong to the same functional 
category. The predictions based on fusion links are shown here for 
Methanobacterium thermoautotrophicum, and another 661 predictions are available 
at http://fusion.bu.edu.