HBV RNA encapsidation signal epsilon

{{Infobox rfam

| Name = HBV RNA encapsidation signal epsilon

| image = HBV_Epsilon.jpg

| width =

| caption = Predicted secondary structure and sequence conservation of HBV_epsilon

| Symbol = HBV_epsilon

| AltSymbols = HBV

| Rfam = RF01047

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| RNA_type = Cis-reg

| Tax_domain = Viruses

| GO = {{GO|0019079}}

| SO = {{SO|0005836}}

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| PDB =

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The HBV RNA encapsidation signal epsilon ([http://rfam.org/family/RF01047 HBV_epsilon]) is an element essential for HBV virus replication.

It is an RNA structure situated near the 5' end of the HBV pregenomic RNA.{{cite journal |vauthors=Beck J, Nassal M |title=Hepatitis B virus replication |journal=World J. Gastroenterol. |volume=13 |issue=1 |pages=48–64 |date=January 2007 |pmid=17206754 |doi=10.3748/wjg.v13.i1.48 |pmc=4065876 |doi-access=free }}

The structure consists of a lower stem, a bulge region, an upper stem and a tri-loop.

The structure was determined and refined through enzymatic probing and NMR spectroscopy.{{cite journal |vauthors=Flodell S, Schleucher J, Cromsigt J, Ippel H, Kidd-Ljunggren K, Wijmenga S |title=The apical stem-loop of the hepatitis B virus encapsidation signal folds into a stable tri-loop with two underlying pyrimidine bulges |journal=Nucleic Acids Res. |volume=30 |issue=21 |pages=4803–4811 |date=November 2002 |pmid=12409471 |pmc=135823 |doi= 10.1093/nar/gkf603|url=}}

The closure of the tri-loop was not predicted by RNA structure prediction programs but observed in the NMR structure.

The regions shown to be critical for encapsidation of the RNA in the viral lifecycle are the bulge, upper stem and tri-loop which interact with the terminal protein domain of the HBV viral polymerase.{{cite journal |vauthors=Kramvis A, Kew MC |title=Structure and function of the encapsidation signal of hepadnaviridae |journal=J. Viral Hepat. |volume=5 |issue=6 |pages=357–367 |date=November 1998 |pmid=9857345 |doi=10.1046/j.1365-2893.1998.00124.x |s2cid=6726175 }}{{cite journal|last=Beck|first=J|author2=Nassal, M|title=Efficient Hsp90-independent in vitro activation by Hsc70 and Hsp40 of duck hepatitis B virus reverse transcriptase, an assumed Hsp90 client protein.|journal=The Journal of Biological Chemistry|year=2003|volume=278|issue=38|pages=36128–36138|pmid=12851401|doi=10.1074/jbc.M301069200|doi-access=free}}