Mapping Contigs Using CONTIGuator

Abstract

Obtaining bacterial genomic sequences has become a routine task in today’s biology. The emergence of the comparative genomics approach has led to an increasing number of bacterial species having more than one strain sequenced, thus facilitating the annotation process. On the other hand, many genomic sequences are now left in the “draft” status, as a series of contigs, mainly for the labor-intensive finishing task. As a result, many genomic analyses are incomplete (e.g., in their annotation) or impossible to be performed (e.g., structural genomics analysis). Many approaches have been recently developed to facilitate the finishing process or at least to produce higher quality scaffolds; taking advantage of the comparative genomics paradigm, closely related genomes are used to align the contigs and determine their relative orientation, thus facilitating the finishing process, but also producing higher quality scaffolds.

In this chapter we present the use of the CONTIGuator algorithm, which aligns the contigs from a draft genome to a closely related closed genome and resolves their relative orientation based on this alignment, producing a scaffold and a series of PCR primer pairs for the finishing process. The CONTIGuator algorithm is also capable of handling multipartite genomes (i.e., genomes having chromosomes and other plasmids), univocally mapping contigs to the most similar replicon. The program also produces a series of contig maps that allow to perform structural genomics analysis on the draft genome. The functionalities of the web interface, as well as the command line version, are presented.