Difference Between Conserved and Consensus Sequence

The key difference between conserved and consensus sequence is that conserved sequence refers to similar sequences of nucleic acids or amino acids that occur in different or same species over generations while consensus sequence is a commonly encountered nucleotides sequence or amino acid sequence found in a highly conserved region of DNA or RNA or protein.

Organisms share similar as well as different characteristics. When studying the relationships between organisms and classifying them, genome or genetic makeup of organisms is very important. There are some nucleotide or amino acid sequences which are common among different organisms. A conserved sequence is a nucleic acid or amino acid sequence which is consistent among species. Therefore, they are phylogenetically important when generating phylogenetic trees. In conserved sequences, there are specific nucleotide sequences that are more commonly found. They are known as consensus sequences.

CONTENTS

1. Overview and Key Difference
2. What is Conserved Sequence
3. What is Consensus Sequence
4. Similarities Between Conserved and Consensus Sequence
5. Side by Side Comparison – Conserved vs Consensus Sequence in Tabular Form
6. Summary

What is Conserved Sequence?

A conserved sequence is a nucleic acid sequence or amino acid sequence that is similar among species. Therefore, it is consistent across the species throughout evolution. Generally, these sequences are maintained by natural selection. They remain unchanged far back up the phylogenetic tree. Hence, conserved sequences are important in constructing phylogenetic trees. It is believed that highly conserved sequences often have an important functional value. They are useful in identifying genetic diseases as well. However, conserved sequences may be coding or non-coding nucleic acid sequences. In addition, conserved sequences show slower rates of mutation. Hence, they show very minimal changes in their composition; sometimes, they don’t show changes all over the generations.

RNA components of ribosomes are present in all domains of life, the homeobox sequences in eukaryotes, and the tmRNA in bacteria are several examples of highly conserved sequences. Identification of conserved sequences is easy when bioinformatics approaches, especially the sequence alignment tool, are used. Moreover, multiple sequence alignment facilitates the visualization of conserved sequences.

What is Consensus Sequence?

A consensus sequence is a sequence that is commonly found in a given conserved region of DNA or RNA. It is a very specific nucleotide sequence. As an example, there is a consensus sequence at the -10 as TATAAT (Pribnow box) in E. coli promoters, which are highly conserved sequences. Similarly, there is another consensus sequence: TTGACA in E. coli promoters at the -35 as well. Consensus sequences are also known as “boxes”.

In addition to DNA and RNA, proteins also have consensus sequences of amino acids. Protein binding sites are often represented by consensus sequences. Restriction enzymes also have consensus sequences. Moreover, splice sites are also consensus sequences. Similar to conserved sequences, consensus sequences can be calculated and visualized by bioinformatics tools.

What are the Similarities Between Conserved and Consensus Sequence?

• Conserved and consensus sequences are nucleic acid or amino acids sequences which are common across species.
• Both conserved and consensus sequences can be visualized by bioinformatics tools.
• They are widely used in molecular biology.

What is the Difference Between Conserved and Consensus Sequence?

The conserved sequence is a nucleic acid or amino acid sequence which is consistent among species while consensus sequences are very specific and commonly found bases or amino acids in a given conserved region. So, this is the key difference between conserved and consensus sequence. Moreover, another difference between conserved and consensus sequence is that the conserved sequences are phylogenetically important while consensus sequences are often protein binding sites, splice sites, restriction enzyme cutting sites, etc.

Summary – Conserved vs Consensus Sequence

Conserved sequences are the sequences of nucleic acids or proteins that are similar among living species. A promoter, ribosome binding site, an origin of replication and amino acid sequence of histone protein are several examples of conserved sequences. In contrast, consensus sequences are specific bases or amino acids which are more commonly found in a given conserved sequence. -10 box, -35 box of E. coli promoter, protein binding sites, splice sites and restriction enzymes recognizing sites are several examples of consensus sequences. Thus, this is the summary of the difference between conserved and consensus sequence.

Reference:

1. “Conserved Sequence”. En.Wikipedia.Org, 2020, Available here.

Image Courtesy:

1. “Histone Alignment” By Thomas Shafee – Own work (CC BY 4.0) via Commons Wikimedia
2. “Kozak consensus sequence” By West0856 at English Wikipedia (CC BY-SA 3.0) via Commons Wikimedia