TY - JOUR
T1 - HU content and dynamics in Escherichia coli during the cell cycle and at different growth rates
AU - Abebe, Anteneh Hailu
AU - Aranovich, Alexander
AU - Fishov, Itzhak
N1 - Funding Information:
This work was performed with financial support from the Israel Science Foundation (ISF grant no. 1701/13 to IF) and in part from the German–Israeli Foundation for Scientific Research and Development (GIF grant no. 1160-137.14/2011 to IF). AA’s salary was covered in part by the Returning Scientist support program of the Israeli Ministry of Immigrant Absorption, and AHA received part of his stipend from the Kreitman School of Advanced Graduate Studies at Ben-Gurion University, Israel.
Publisher Copyright:
© FEMS 2017. All rights reserved.
PY - 2017/10/1
Y1 - 2017/10/1
N2 - DNA-binding proteins play an important role in maintaining bacterial chromosome structure and functions. Heat-unstable (HU) histone-like protein is one of the most abundant of these proteins and participates in all major chromosome-related activities. Owing to its low sequence specificity, HU fusions with fluorescent proteins were used for general staining of the nucleoid, aiming to reveal its morphology and dynamics. We have exploited a single chromosomal copy of hupA-egfp fusion under the native promoter and used quantitative microscopy imaging to investigate the amount and dynamics of HUα in Escherichia coli cells. We found that in steady-state growing populations the cellular HUα content is proportional to the cell size, whereas its concentration is size independent. Single-cell live microscopy imaging confirmed that the amount of HUα exponentially increases during the cell cycle, but its concentration is maintained constant. This supports the existence of an auto-regulatory mechanism underlying the HUα cellular level, in addition to reflecting the gene copy number. Both the HUα amount and concentration strongly increase with the cell growth rate in different culture media. Unexpectedly, the HU/DNA stoichiometry also remarkably increases with the growth rate. This last finding may be attributed to a higher requirement for maintaining the chromosome structure in nucleoids with higher complexity.
AB - DNA-binding proteins play an important role in maintaining bacterial chromosome structure and functions. Heat-unstable (HU) histone-like protein is one of the most abundant of these proteins and participates in all major chromosome-related activities. Owing to its low sequence specificity, HU fusions with fluorescent proteins were used for general staining of the nucleoid, aiming to reveal its morphology and dynamics. We have exploited a single chromosomal copy of hupA-egfp fusion under the native promoter and used quantitative microscopy imaging to investigate the amount and dynamics of HUα in Escherichia coli cells. We found that in steady-state growing populations the cellular HUα content is proportional to the cell size, whereas its concentration is size independent. Single-cell live microscopy imaging confirmed that the amount of HUα exponentially increases during the cell cycle, but its concentration is maintained constant. This supports the existence of an auto-regulatory mechanism underlying the HUα cellular level, in addition to reflecting the gene copy number. Both the HUα amount and concentration strongly increase with the cell growth rate in different culture media. Unexpectedly, the HU/DNA stoichiometry also remarkably increases with the growth rate. This last finding may be attributed to a higher requirement for maintaining the chromosome structure in nucleoids with higher complexity.
KW - Bacterial cell cycle
KW - Cell growth rate
KW - Escherichia coli
KW - Histone-like protein HU
KW - Hup-egfp
KW - Nucleoid complexity
UR - http://www.scopus.com/inward/record.url?scp=85032807022&partnerID=8YFLogxK
U2 - 10.1093/femsle/fnx195
DO - 10.1093/femsle/fnx195
M3 - Letter
C2 - 28961819
AN - SCOPUS:85032807022
SN - 0378-1097
VL - 364
JO - FEMS Microbiology Letters
JF - FEMS Microbiology Letters
IS - 19
M1 - fnx195
ER -