How does the promoter determine which DNA strand is “coding” and “template”? Is the coding strand used by RNA?

How does the promoter determine which DNA strand is “coding” and “template”? Is the coding strand used by RNA polymerase?





May someone explain this to me in a easy to understand explanation. Thanks in advance!How does the promoter determine which DNA strand is “coding” and “template”? Is the coding strand used by RNA?
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The RNA Polymerase is holoenzyme and has a molecular wt. of 4,80,000. Its subunit composition is a,b,b' and s (sigma). the holoenzyme can be separated into two components, the core enzyme and the sigma factor (9 polypeptide). It requires template of double strand DNA or occasionally a single stranded DNA, four ribonucleotide triphosphates GTP, ATP, UTP, CTP and Mg+ or Mn. Recognized by RNA polymerase are called promoter. The size of the promoter region is variable. In prokaryates it varies from 20-200 bases. Core enzyme can not recognize the promoter region, sigma factor is required for recognition and formation of the complex. It occurs in four steps :


(i) Sigma factor recognizes the promoter sequences.


(ii) RNA polymerase attaches to promoter region.


(iii) RNA polymernse melts the helical structure and separates two strands of DNA locally.


(iv) RNA polymerase initiates RNA synthesis.


The site at which the first nudeotide is incorporated is called the start site or initiation point.


There are few specific characteristics of promoter sequence :


a. The Pribnow box (after the name of its discover, David Pribnow) or-10 box is a sequence contained with the promoter region. It is located 5-10 bases to the left, i.e., upstream the first four bases that will be copied into RNA. It orients RNA polymerase as to the direction and start of synthesis.


b. All Pribnow boxes are variants of TATAATG sequences and sometimes referred to as TATA box. Typically it contains nine bases.


c. Since the RNA polymerase has a huge size, it comes into contact with Pribnow box.


d. Once bound to the Prinbox box, RNA polymerase dissociates from the initial recognition site.


e. This complex is active intermediate in RNA chain initiation. The important event is the melting of DNA duplex that takes place about 10 bases pairs upstream of TATA box and extending to the first transcribe base at the start point.


For further deatils check in this link:


http://www.wiziq.com/tutorial/32754-TATA…How does the promoter determine which DNA strand is “coding” and “template”? Is the coding strand used by RNA?
DNA has two strands. Both strands are the opposite of each other so they match like a puzzle. A promoter is the exact same and is the opposite of the region of DNA it wishes to began coding. It will only bind to the region that is its exact opposite. So if the promoter is GGGCCC it will ONLY bind to DNA that is CCCGGG. It will not be able to bind to anything else.

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